diff --git a/eslint.config.mjs b/eslint.config.mjs
index 165d111b22..fb95dab779 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -41,9 +41,8 @@ export default [
       '**/type-test.ts',
       'packages/**/modular/dist/**/*',
       'packages/ai/__tests__/test-utils',
+      'packages/**/dist/**/*',
       'packages/vertexai/__tests__/test-utils',
-      'packages/vertexai/dist',
-      'packages/ai/dist',
     ],
   },
   ...compat
diff --git a/jest.setup.ts b/jest.setup.ts
index cc15b33e9b..e04af31fc6 100644
--- a/jest.setup.ts
+++ b/jest.setup.ts
@@ -39,6 +39,20 @@ jest.doMock('react-native', () => {
         ...ReactNative.NativeModules,
         RNFBAnalyticsModule: {
           logEvent: jest.fn(),
+          setAnalyticsCollectionEnabled: jest.fn(),
+          setSessionTimeoutDuration: jest.fn(),
+          getAppInstanceId: jest.fn(),
+          getSessionId: jest.fn(),
+          setUserId: jest.fn(),
+          setUserProperty: jest.fn(),
+          setUserProperties: jest.fn(),
+          resetAnalyticsData: jest.fn(),
+          setConsent: jest.fn(),
+          setDefaultEventParameters: jest.fn(),
+          initiateOnDeviceConversionMeasurementWithEmailAddress: jest.fn(),
+          initiateOnDeviceConversionMeasurementWithHashedEmailAddress: jest.fn(),
+          initiateOnDeviceConversionMeasurementWithPhoneNumber: jest.fn(),
+          initiateOnDeviceConversionMeasurementWithHashedPhoneNumber: jest.fn(),
         },
         RNFBAppModule: {
           NATIVE_FIREBASE_APPS: [
@@ -67,32 +81,346 @@ jest.doMock('react-native', () => {
             '[DEFAULT]': 'en-US',
           },
           APP_USER: {
-            '[DEFAULT]': 'jestUser',
+            '[DEFAULT]': null,
           },
           addAuthStateListener: jest.fn(),
           addIdTokenListener: jest.fn(),
-          setTenantId: jest.fn(),
+          setLanguageCode: jest.fn(() => Promise.resolve()),
+          setTenantId: jest.fn(() => Promise.resolve()),
+          signOut: jest.fn(() => Promise.resolve()),
+          signInAnonymously: jest.fn(() => Promise.resolve({ user: null })),
+          createUserWithEmailAndPassword: jest.fn(() => Promise.resolve({ user: null })),
+          signInWithEmailAndPassword: jest.fn(() => Promise.resolve({ user: null })),
+          signInWithCustomToken: jest.fn(() => Promise.resolve({ user: null })),
+          signInWithCredential: jest.fn(() => Promise.resolve({ user: null })),
+          signInWithEmailLink: jest.fn(() => Promise.resolve({ user: null })),
+          signInWithProvider: jest.fn(() => Promise.resolve({ user: null })),
+          signInWithPhoneNumber: jest.fn(() => Promise.resolve({ verificationId: 'test-id' })),
+          verifyPhoneNumberWithMultiFactorInfo: jest.fn(() => Promise.resolve()),
+          verifyPhoneNumberForMultiFactor: jest.fn(() => Promise.resolve()),
+          resolveTotpSignIn: jest.fn(() => Promise.resolve({})),
+          revokeToken: jest.fn(() => Promise.resolve()),
+          sendPasswordResetEmail: jest.fn(() => Promise.resolve()),
+          sendSignInLinkToEmail: jest.fn(() => Promise.resolve()),
+          isSignInWithEmailLink: jest.fn(() => false),
+          applyActionCode: jest.fn(() => Promise.resolve(null)),
+          checkActionCode: jest.fn(() => Promise.resolve({})),
+          confirmPasswordReset: jest.fn(() => Promise.resolve()),
+          fetchSignInMethodsForEmail: jest.fn(() => Promise.resolve([])),
+          verifyPasswordResetCode: jest.fn(() => Promise.resolve('')),
+          useUserAccessGroup: jest.fn(() => Promise.resolve()),
           useEmulator: jest.fn(),
-          configureAuthDomain: jest.fn(),
+          getCustomAuthDomain: jest.fn(() => Promise.resolve(null)),
+          configureAuthDomain: jest.fn(() => Promise.resolve()),
+          // User methods
+          delete: jest.fn(() => Promise.resolve()),
+          getIdToken: jest.fn(() => Promise.resolve('mock-token')),
+          getIdTokenResult: jest.fn(() => Promise.resolve({ token: 'mock-token' })),
+          linkWithCredential: jest.fn(() => Promise.resolve({ user: null })),
+          linkWithProvider: jest.fn(() => Promise.resolve({ user: null })),
+          reauthenticateWithCredential: jest.fn(() => Promise.resolve({ user: null })),
+          reauthenticateWithProvider: jest.fn(() => Promise.resolve({ user: null })),
+          reload: jest.fn(() => Promise.resolve(null)),
+          sendEmailVerification: jest.fn(() => Promise.resolve(null)),
+          unlink: jest.fn(() => Promise.resolve(null)),
+          updateEmail: jest.fn(() => Promise.resolve(null)),
+          updatePassword: jest.fn(() => Promise.resolve(null)),
+          updatePhoneNumber: jest.fn(() => Promise.resolve(null)),
+          updateProfile: jest.fn(() => Promise.resolve(null)),
+          verifyBeforeUpdateEmail: jest.fn(() => Promise.resolve(null)),
+        },
+        RNFBAppCheckModule: {
+          initializeAppCheck: jest.fn(),
+          setTokenAutoRefreshEnabled: jest.fn(),
+          configureProvider: jest.fn(),
+          getToken: jest.fn(),
+          getLimitedUseToken: jest.fn(),
+          addAppCheckListener: jest.fn(),
+          removeAppCheckListener: jest.fn(),
+        },
+        RNFBAppDistributionModule: {
+          isTesterSignedIn: jest.fn(),
+          signInTester: jest.fn(),
+          checkForUpdate: jest.fn(),
+          signOutTester: jest.fn(),
+        },
+        RNFBCrashlyticsModule: {
+          isCrashlyticsCollectionEnabled: false,
+          checkForUnsentReports: jest.fn(),
+          crash: jest.fn(),
+          deleteUnsentReports: jest.fn(),
+          didCrashOnPreviousExecution: jest.fn(),
+          log: jest.fn(),
+          setAttribute: jest.fn(),
+          setAttributes: jest.fn(),
+          setUserId: jest.fn(),
+          recordError: jest.fn(),
+          sendUnsentReports: jest.fn(),
+          setCrashlyticsCollectionEnabled: jest.fn(),
         },
-        RNFBCrashlyticsModule: {},
         RNFBDatabaseModule: {
+          constants: {
+            isDatabaseCollectionEnabled: true,
+            url: 'https://test.firebaseio.com',
+            ref: 'ref()',
+          },
           on: jest.fn(),
-          useEmulator: jest.fn(),
+          off: jest.fn(),
+          once: jest.fn(
+            (_appName: any, _customUrl: any, path: any, _modifiers: any, eventType: any) => {
+              // Database native methods receive (appName, customUrlOrRegion, ...actualArgs)
+              let key = 'test';
+              if (path && typeof path === 'string') {
+                const parts = path.split('/').filter(p => p);
+                key = parts[parts.length - 1] || 'test';
+              }
+
+              const snapshotData = {
+                key,
+                value: null,
+                exists: false,
+                childKeys: [],
+                priority: null,
+              };
+
+              if (eventType === 'value') {
+                return Promise.resolve(snapshotData);
+              }
+
+              return Promise.resolve({
+                snapshot: snapshotData,
+                previousChildName: null,
+              });
+            },
+          ),
+          useEmulator: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          set: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          update: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          setWithPriority: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          remove: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          setPriority: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          keepSynced: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          transactionStart: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          transactionTryCommit: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          goOnline: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          goOffline: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          setPersistenceEnabled: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          setLoggingEnabled: jest.fn((_appName: any, _customUrl: any) => Promise.resolve()),
+          setPersistenceCacheSizeBytes: jest.fn((_appName: any, _customUrl: any) =>
+            Promise.resolve(),
+          ),
+          getServerTime: jest.fn((_appName: any, _customUrl: any) => Promise.resolve(Date.now())),
         },
         RNFBFirestoreModule: {
+          loadBundle: jest.fn(),
+          clearPersistence: jest.fn(),
+          waitForPendingWrites: jest.fn(),
+          terminate: jest.fn(),
+          useEmulator: jest.fn(),
+          disableNetwork: jest.fn(),
+          enableNetwork: jest.fn(),
           settings: jest.fn(),
-          documentSet: jest.fn(),
+          addSnapshotsInSync: jest.fn(),
+          removeSnapshotsInSync: jest.fn(),
+          collectionOffSnapshot: jest.fn(),
+          namedQueryOnSnapshot: jest.fn(),
+          collectionOnSnapshot: jest.fn(),
+          collectionGet: jest.fn(() =>
+            Promise.resolve({
+              source: 'cache',
+              changes: [],
+              documents: [],
+              metadata: {},
+            }),
+          ),
+          collectionCount: jest.fn(() => Promise.resolve({ count: 0 })),
+          documentDelete: jest.fn(() => Promise.resolve()),
+          documentOffSnapshot: jest.fn(),
+          documentOnSnapshot: jest.fn(),
+          documentGet: jest.fn(() =>
+            Promise.resolve({
+              data: {},
+              metadata: {},
+              path: 'firestore/document',
+              exists: true,
+            }),
+          ),
+          documentSet: jest.fn(() => Promise.resolve()),
+          documentUpdate: jest.fn(() => Promise.resolve()),
+          persistenceCacheIndexManager: jest.fn(),
+          documentBatch: jest.fn(),
+          transactionApplyBuffer: jest.fn(),
+          transactionBegin: jest.fn(),
+          transactionDispose: jest.fn(),
+        },
+        RNFBInAppMessagingModule: {
+          isMessagesDisplaySuppressed: false,
+          isAutomaticDataCollectionEnabled: true,
+          setMessagesDisplaySuppressed: jest.fn(),
+          setAutomaticDataCollectionEnabled: jest.fn(),
+          triggerEvent: jest.fn(),
+        },
+        RNFBInstallationsModule: {
+          getId: jest.fn(),
+          getToken: jest.fn(),
+          delete: jest.fn(),
         },
         RNFBMessagingModule: {
+          isAutoInitEnabled: true,
+          isDeliveryMetricsExportToBigQueryEnabled: false,
+          isRegisteredForRemoteNotifications: false,
+          isNotificationDelegationEnabled: false,
           onMessage: jest.fn(),
+          completeNotificationProcessing: jest.fn(),
+          setAutoInitEnabled: jest.fn(),
+          getInitialNotification: jest.fn(() => Promise.resolve(null)),
+          getDidOpenSettingsForNotification: jest.fn(() => Promise.resolve(false)),
+          getIsHeadless: jest.fn(() => Promise.resolve(false)),
+          getToken: jest.fn(),
+          deleteToken: jest.fn(),
+          requestPermission: jest.fn(() => Promise.resolve(1)),
+          registerForRemoteNotifications: jest.fn(),
+          unregisterForRemoteNotifications: jest.fn(),
+          getAPNSToken: jest.fn(),
+          setAPNSToken: jest.fn(),
+          hasPermission: jest.fn(() => Promise.resolve(1)),
+          signalBackgroundMessageHandlerSet: jest.fn(),
+          sendMessage: jest.fn(),
+          subscribeToTopic: jest.fn(),
+          unsubscribeFromTopic: jest.fn(),
+          setDeliveryMetricsExportToBigQuery: jest.fn(),
+          setNotificationDelegationEnabled: jest.fn(),
+        },
+        RNFBPerfModule: {
+          isPerformanceCollectionEnabled: true,
+          isInstrumentationEnabled: true,
+          instrumentationEnabled: jest.fn(() => Promise.resolve()),
+          setPerformanceCollectionEnabled: jest.fn(() => Promise.resolve()),
+          startScreenTrace: jest.fn(() => Promise.resolve()),
+          stopScreenTrace: jest.fn(() => Promise.resolve()),
+          startTrace: jest.fn(() => Promise.resolve()),
+          stopTrace: jest.fn(() => Promise.resolve()),
+          startHttpMetric: jest.fn(() => Promise.resolve()),
+          stopHttpMetric: jest.fn(() => Promise.resolve()),
         },
-        RNFBPerfModule: {},
         RNFBConfigModule: {
           onConfigUpdated: jest.fn(),
+          reset: jest.fn(() =>
+            Promise.resolve({
+              result: true,
+              constants: {
+                lastFetchTime: Date.now(),
+                lastFetchStatus: 'success',
+                fetchTimeout: 60,
+                minimumFetchInterval: 43200,
+                values: {},
+              },
+            }),
+          ),
+          setConfigSettings: jest.fn(() =>
+            Promise.resolve({
+              result: true,
+              constants: {
+                lastFetchTime: Date.now(),
+                lastFetchStatus: 'success',
+                fetchTimeout: 60,
+                minimumFetchInterval: 43200,
+                values: {},
+              },
+            }),
+          ),
+          activate: jest.fn(() =>
+            Promise.resolve({
+              result: true,
+              constants: {
+                lastFetchTime: Date.now(),
+                lastFetchStatus: 'success',
+                fetchTimeout: 60,
+                minimumFetchInterval: 43200,
+                values: {},
+              },
+            }),
+          ),
+          fetch: jest.fn(() =>
+            Promise.resolve({
+              result: true,
+              constants: {
+                lastFetchTime: Date.now(),
+                lastFetchStatus: 'success',
+                fetchTimeout: 60,
+                minimumFetchInterval: 43200,
+                values: {},
+              },
+            }),
+          ),
+          fetchAndActivate: jest.fn(() =>
+            Promise.resolve({
+              result: true,
+              constants: {
+                lastFetchTime: Date.now(),
+                lastFetchStatus: 'success',
+                fetchTimeout: 60,
+                minimumFetchInterval: 43200,
+                values: {},
+              },
+            }),
+          ),
+          ensureInitialized: jest.fn(() =>
+            Promise.resolve({
+              result: true,
+              constants: {
+                lastFetchTime: Date.now(),
+                lastFetchStatus: 'success',
+                fetchTimeout: 60,
+                minimumFetchInterval: 43200,
+                values: {},
+              },
+            }),
+          ),
+          setDefaults: jest.fn(() =>
+            Promise.resolve({
+              result: true,
+              constants: {
+                lastFetchTime: Date.now(),
+                lastFetchStatus: 'success',
+                fetchTimeout: 60,
+                minimumFetchInterval: 43200,
+                values: {},
+              },
+            }),
+          ),
+          setDefaultsFromResource: jest.fn(() =>
+            Promise.resolve({
+              result: true,
+              constants: {
+                lastFetchTime: Date.now(),
+                lastFetchStatus: 'success',
+                fetchTimeout: 60,
+                minimumFetchInterval: 43200,
+                values: {},
+              },
+            }),
+          ),
+          removeConfigUpdateRegistration: jest.fn(),
         },
         RNFBStorageModule: {
+          maxUploadRetryTime: 0,
+          maxDownloadRetryTime: 0,
+          maxOperationRetryTime: 0,
+          setMaxOperationRetryTime: jest.fn(),
+          setMaxUploadRetryTime: jest.fn(),
+          setMaxDownloadRetryTime: jest.fn(),
           useEmulator: jest.fn(),
+          delete: jest.fn(() => Promise.resolve()),
+          getDownloadURL: jest.fn(() => Promise.resolve('https://example.com/file')),
+          getMetadata: jest.fn(() => Promise.resolve({})),
+          putString: jest.fn(() => Promise.resolve()),
+          updateMetadata: jest.fn(() => Promise.resolve({})),
+          writeToFile: jest.fn(() => Promise.resolve()),
+          putFile: jest.fn(() => Promise.resolve()),
+          setTaskStatus: jest.fn(() => Promise.resolve()),
+          list: jest.fn(() => Promise.resolve({ items: [], prefixes: [], pageToken: null })),
+          listAll: jest.fn(() => Promise.resolve({ items: [], prefixes: [], pageToken: null })),
         },
       },
     },
diff --git a/packages/ai/tsconfig.json b/packages/ai/tsconfig.json
index f1d9865812..b40f80b289 100644
--- a/packages/ai/tsconfig.json
+++ b/packages/ai/tsconfig.json
@@ -6,9 +6,7 @@
     "esModuleInterop": true,
     "forceConsistentCasingInFileNames": true,
     "jsx": "react-jsx",
-    "lib": [
-      "ESNext"
-    ],
+    "lib": ["ESNext"],
     "module": "ESNext",
     "target": "ESNext",
     "moduleResolution": "Bundler",
@@ -24,9 +22,20 @@
     "strict": true,
     "baseUrl": ".",
     "paths": {
-      "@react-native-firebase/app": ["../app/lib"],
+      "@react-native-firebase/app/lib/common/*": ["../app/dist/typescript/commonjs/lib/common/*"],
+      "@react-native-firebase/app/lib/common": ["../app/dist/typescript/commonjs/lib/common"],
+      "@react-native-firebase/app/lib/internal/web/*": [
+        "../app/dist/typescript/commonjs/lib/internal/web/*"
+      ],
+      "@react-native-firebase/app/lib/internal/*": [
+        "../app/dist/typescript/commonjs/lib/internal/*"
+      ],
+      "@react-native-firebase/app/lib/internal": ["../app/dist/typescript/commonjs/lib/internal"],
+      "@react-native-firebase/app": ["../app/dist/typescript/commonjs/lib"],
       "@react-native-firebase/auth": ["../auth/lib"],
-      "@react-native-firebase/app-check": ["../app-check/lib"],
+      "@react-native-firebase/app-check": ["../app-check/lib"]
     }
-  }
+  },
+  "include": ["lib/**/*"],
+  "exclude": ["node_modules", "dist", "__tests__", "**/*.test.ts"]
 }
diff --git a/packages/app/lib/FirebaseApp.js b/packages/app/lib/FirebaseApp.ts
similarity index 59%
rename from packages/app/lib/FirebaseApp.js
rename to packages/app/lib/FirebaseApp.ts
index 841138702c..247c538081 100644
--- a/packages/app/lib/FirebaseApp.js
+++ b/packages/app/lib/FirebaseApp.ts
@@ -14,12 +14,26 @@
  * limitations under the License.
  *
  */
-import { warnIfNotModularCall } from '@react-native-firebase/app/lib/common';
+import { warnIfNotModularCall } from './common';
 import { getAppModule } from './internal/registry/nativeModule';
+import type { ReactNativeFirebase, Utils } from './types/app';
 
-export default class FirebaseApp {
-  constructor(options, appConfig, fromNative, deleteApp) {
-    const { name, automaticDataCollectionEnabled } = appConfig;
+export default class FirebaseApp implements ReactNativeFirebase.FirebaseAppBase {
+  private _name: string;
+  private _deleted: boolean;
+  private _deleteApp: () => Promise<void>;
+  private _options: ReactNativeFirebase.FirebaseAppOptions;
+  private _automaticDataCollectionEnabled: boolean;
+  _initialized: boolean;
+  _nativeInitialized: boolean;
+
+  constructor(
+    options: ReactNativeFirebase.FirebaseAppOptions,
+    appConfig: ReactNativeFirebase.FirebaseAppConfig,
+    fromNative: boolean,
+    deleteApp: () => Promise<void>,
+  ) {
+    const { name = '[DEFAULT]', automaticDataCollectionEnabled } = appConfig;
 
     this._name = name;
     this._deleted = false;
@@ -36,44 +50,49 @@ export default class FirebaseApp {
     }
   }
 
-  get name() {
+  get name(): string {
     return this._name;
   }
 
-  get options() {
+  get options(): ReactNativeFirebase.FirebaseAppOptions {
     return Object.assign({}, this._options);
   }
 
-  get automaticDataCollectionEnabled() {
+  get automaticDataCollectionEnabled(): boolean {
     return this._automaticDataCollectionEnabled;
   }
 
-  set automaticDataCollectionEnabled(enabled) {
+  set automaticDataCollectionEnabled(enabled: boolean) {
     this._checkDestroyed();
     getAppModule().setAutomaticDataCollectionEnabled(this.name, enabled);
     this._automaticDataCollectionEnabled = enabled;
   }
 
-  _checkDestroyed() {
+  private _checkDestroyed(): void {
     if (this._deleted) {
       throw new Error(`Firebase App named '${this._name}' already deleted`);
     }
   }
 
-  extendApp(extendedProps) {
+  extendApp(extendedProps: Record<string, unknown>): void {
     warnIfNotModularCall(arguments);
     this._checkDestroyed();
     Object.assign(this, extendedProps);
   }
 
-  delete() {
+  delete(): Promise<void> {
     warnIfNotModularCall(arguments, 'deleteApp()');
     this._checkDestroyed();
     return this._deleteApp();
   }
 
-  toString() {
+  toString(): string {
     warnIfNotModularCall(arguments, '.name property');
     return this.name;
   }
+
+  // For backward compatibility - utils method added by registry
+  utils(): Utils.Module {
+    throw new Error('utils() should be added by registry');
+  }
 }
diff --git a/packages/app/lib/common/Base64.js b/packages/app/lib/common/Base64.ts
similarity index 76%
rename from packages/app/lib/common/Base64.js
rename to packages/app/lib/common/Base64.ts
index 6c12c6efb5..707d7f1796 100644
--- a/packages/app/lib/common/Base64.js
+++ b/packages/app/lib/common/Base64.ts
@@ -15,6 +15,7 @@
  *
  */
 
+// @ts-expect-error - No type declarations available
 import binaryToBase64 from 'react-native/Libraries/Utilities/binaryToBase64';
 import { promiseDefer } from './promise';
 
@@ -23,7 +24,7 @@ const CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=
 /**
  * window.btoa
  */
-function btoa(input) {
+function btoa(input: string): string {
   let map;
   let i = 0;
   let block = 0;
@@ -51,11 +52,11 @@ function btoa(input) {
 /**
  * window.atob
  */
-function atob(input) {
+function atob(input: string): string {
   let i = 0;
   let bc = 0;
   let bs = 0;
-  let buffer;
+  let buffer: number | string;
   let output = '';
 
   const str = input.replace(/[=]+$/, '');
@@ -69,7 +70,7 @@ function atob(input) {
   for (
     bc = 0, bs = 0, i = 0;
     (buffer = str.charAt(i++));
-    ~buffer && ((bs = bc % 4 ? bs * 64 + buffer : buffer), bc++ % 4)
+    ~buffer && ((bs = bc % 4 ? bs * 64 + (buffer as number) : buffer), bc++ % 4)
       ? (output += String.fromCharCode(255 & (bs >> ((-2 * bc) & 6))))
       : 0
   ) {
@@ -79,23 +80,30 @@ function atob(input) {
   return output;
 }
 
+export interface Base64Result {
+  string: string | ArrayBuffer | null;
+  format: 'data_url' | 'base64';
+}
+
 /**
  * Converts a Blob, ArrayBuffer or Uint8Array to a base64 string.
  */
-function fromData(data) {
+function fromData(data: Blob | ArrayBuffer | Uint8Array): Promise<Base64Result> {
   if (data instanceof Blob) {
     const fileReader = new FileReader();
-    const { resolve, reject, promise } = promiseDefer();
+    const { resolve, reject, promise } = promiseDefer<Base64Result>();
 
     fileReader.readAsDataURL(data);
 
-    fileReader.onloadend = function onloadend() {
-      resolve({ string: fileReader.result, format: 'data_url' });
+    fileReader.onloadend = () => {
+      if (fileReader?.result) {
+        resolve?.({ string: fileReader.result, format: 'data_url' });
+      }
     };
 
-    fileReader.onerror = function onerror(event) {
-      fileReader.abort();
-      reject(event);
+    fileReader.onerror = event => {
+      fileReader?.abort();
+      reject?.(event);
     };
 
     return promise;
diff --git a/packages/app/lib/common/MutatableParams.js b/packages/app/lib/common/MutatableParams.ts
similarity index 75%
rename from packages/app/lib/common/MutatableParams.js
rename to packages/app/lib/common/MutatableParams.ts
index 8b998dade5..8078e4ea52 100644
--- a/packages/app/lib/common/MutatableParams.js
+++ b/packages/app/lib/common/MutatableParams.ts
@@ -18,7 +18,10 @@
 import { deepGet, deepSet } from './deeps';
 
 export default class MutatableParams {
-  constructor(parentInstance) {
+  _mutatableParams: Record<string, unknown>;
+  _parentInstance: MutatableParams;
+
+  constructor(parentInstance?: MutatableParams) {
     if (parentInstance) {
       this._mutatableParams = parentInstance._mutatableParams;
       this._parentInstance = parentInstance;
@@ -28,20 +31,20 @@ export default class MutatableParams {
     }
   }
 
-  set(param, value) {
+  set(param: string, value: unknown): MutatableParams {
     deepSet(this._mutatableParams, param, value);
     return this._parentInstance;
   }
 
-  get(param) {
-    return deepGet(this._mutatableParams, param, '.');
+  get<T = unknown>(param: string): T | undefined {
+    return deepGet<T>(this._mutatableParams, param, '.');
   }
 
-  toJSON() {
+  toJSON(): Record<string, unknown> {
     return Object.assign({}, this._mutatableParams);
   }
 
-  validate() {
+  validate(): void {
     // do nothing
   }
 }
diff --git a/packages/app/lib/common/ReferenceBase.js b/packages/app/lib/common/ReferenceBase.ts
similarity index 94%
rename from packages/app/lib/common/ReferenceBase.js
rename to packages/app/lib/common/ReferenceBase.ts
index 0fe24f608a..5e73ba5e86 100644
--- a/packages/app/lib/common/ReferenceBase.js
+++ b/packages/app/lib/common/ReferenceBase.ts
@@ -16,7 +16,9 @@
  */
 
 export default class ReferenceBase {
-  constructor(_path) {
+  path: string;
+
+  constructor(_path: string) {
     let path = _path;
 
     if (path) {
@@ -37,7 +39,7 @@ export default class ReferenceBase {
    * @type {String}
    * {@link https://firebase.google.com/docs/reference/js/firebase.database.Reference#key}
    */
-  get key() {
+  get key(): string | null {
     return this.path === '/' ? null : this.path.substring(this.path.lastIndexOf('/') + 1);
   }
 }
diff --git a/packages/app/lib/common/deeps.js b/packages/app/lib/common/deeps.ts
similarity index 70%
rename from packages/app/lib/common/deeps.js
rename to packages/app/lib/common/deeps.ts
index cf235c376b..8ca859ac99 100644
--- a/packages/app/lib/common/deeps.js
+++ b/packages/app/lib/common/deeps.ts
@@ -25,25 +25,29 @@ import { isArray, isObject } from './validate';
  * @param joiner
  * @returns {*}
  */
-export function deepGet(object, path, joiner = '/') {
+export function deepGet<T = unknown>(
+  object: Record<string, unknown> | unknown[],
+  path: string,
+  joiner: string = '/',
+): T | undefined {
   if (!isObject(object) && !Array.isArray(object)) {
     return undefined;
   }
   const keys = path.split(joiner);
 
   let i = 0;
-  let tmp = object;
+  let tmp: unknown = object;
   const len = keys.length;
 
   while (i < len) {
-    const key = keys[i++];
+    const key = keys[i++]!;
     if (!tmp || !Object.hasOwnProperty.call(tmp, key)) {
       return undefined;
     }
-    tmp = tmp[key];
+    tmp = (tmp as Record<string, unknown>)[key];
   }
 
-  return tmp;
+  return tmp as T;
 }
 
 /**
@@ -54,26 +58,32 @@ export function deepGet(object, path, joiner = '/') {
  * @param initPaths
  * @param joiner
  */
-export function deepSet(object, path, value, initPaths = true, joiner = '.') {
+export function deepSet(
+  object: Record<string, unknown>,
+  path: string,
+  value: unknown,
+  initPaths: boolean = true,
+  joiner: string = '.',
+): boolean {
   if (!isObject(object)) {
     return false;
   }
   const keys = path.split(joiner);
 
   let i = 0;
-  let _object = object;
+  let _object: unknown = object;
   const len = keys.length - 1;
 
   while (i < len) {
-    const key = keys[i++];
+    const key = keys[i++]!;
     if (initPaths && !Object.hasOwnProperty.call(object, key)) {
-      _object[key] = {};
+      (_object as Record<string, unknown>)[key] = {};
     }
-    _object = _object[key];
+    _object = (_object as Record<string, unknown>)[key];
   }
 
   if (isObject(_object) || (isArray(_object) && !Number.isNaN(keys[i]))) {
-    _object[keys[i]] = value;
+    (_object as Record<string, unknown>)[keys[i]!] = value;
   } else {
     return false;
   }
diff --git a/packages/app/lib/common/id.js b/packages/app/lib/common/id.ts
similarity index 69%
rename from packages/app/lib/common/id.js
rename to packages/app/lib/common/id.ts
index 1266cb815b..568f33ef52 100644
--- a/packages/app/lib/common/id.js
+++ b/packages/app/lib/common/id.ts
@@ -1,3 +1,20 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
 const PUSH_CHARS = '-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz';
 
 const AUTO_ID_CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
@@ -9,14 +26,14 @@ let lastPushTime = 0;
 // timestamp to prevent collisions with other clients.  We store the last characters we
 // generated because in the event of a collision, we'll use those same characters except
 // "incremented" by one.
-const lastRandChars = [];
+const lastRandChars: number[] = [];
 
 /**
  * Generate a firebase id - for use with ref().push(val, cb) - e.g. -KXMr7k2tXUFQqiaZRY4'
  * @param serverTimeOffset - pass in server time offset from native side
  * @returns {string}
  */
-export function generateDatabaseId(serverTimeOffset = 0) {
+export function generateDatabaseId(serverTimeOffset: number = 0): string {
   const timeStampChars = new Array(8);
   let now = new Date().getTime() + serverTimeOffset;
   const duplicateTime = now === lastPushTime;
@@ -46,11 +63,11 @@ export function generateDatabaseId(serverTimeOffset = 0) {
       lastRandChars[i] = 0;
     }
 
-    lastRandChars[i] += 1;
+    lastRandChars[i]! += 1;
   }
 
   for (let i = 0; i < 12; i++) {
-    id += PUSH_CHARS.charAt(lastRandChars[i]);
+    id += PUSH_CHARS.charAt(lastRandChars[i]!);
   }
 
   if (id.length !== 20) {
@@ -64,7 +81,7 @@ export function generateDatabaseId(serverTimeOffset = 0) {
  * Generate a firestore auto id for use with collection/document .add()
  * @return {string}
  */
-export function generateFirestoreId() {
+export function generateFirestoreId(): string {
   let autoId = '';
 
   for (let i = 0; i < 20; i++) {
diff --git a/packages/app/lib/common/index.js b/packages/app/lib/common/index.ts
similarity index 89%
rename from packages/app/lib/common/index.js
rename to packages/app/lib/common/index.ts
index 08afb367c2..585f075ccc 100644
--- a/packages/app/lib/common/index.js
+++ b/packages/app/lib/common/index.ts
@@ -17,6 +17,7 @@
 import { Platform } from 'react-native';
 import Base64 from './Base64';
 import { isFunction, isObject, isString } from './validate';
+import type { DataUrlParts, Observer } from '../types/internal';
 
 export * from './id';
 export * from './path';
@@ -26,7 +27,9 @@ export * from './validate';
 export { default as Base64 } from './Base64';
 export { default as ReferenceBase } from './ReferenceBase';
 
-export function getDataUrlParts(dataUrlString) {
+export type { DataUrlParts, Observer };
+
+export function getDataUrlParts(dataUrlString: string): DataUrlParts {
   const isBase64 = dataUrlString.includes(';base64');
   let [mediaType, base64String] = dataUrlString.split(',');
   if (!mediaType || !base64String) {
@@ -42,11 +45,14 @@ export function getDataUrlParts(dataUrlString) {
   return { base64String, mediaType };
 }
 
-export function once(fn, context) {
-  let onceResult;
+export function once<T extends (...args: any[]) => any>(
+  fn: T,
+  context?: any,
+): (...args: Parameters<T>) => ReturnType<T> {
+  let onceResult: ReturnType<T>;
   let ranOnce = false;
 
-  return function onceInner(...args) {
+  return function onceInner(this: any, ...args: Parameters<T>): ReturnType<T> {
     if (!ranOnce) {
       ranOnce = true;
       onceResult = fn.apply(context || this, args);
@@ -56,7 +62,7 @@ export function once(fn, context) {
   };
 }
 
-export function isError(value) {
+export function isError(value: any): value is Error {
   if (Object.prototype.toString.call(value) === '[object Error]') {
     return true;
   }
@@ -64,7 +70,7 @@ export function isError(value) {
   return value instanceof Error;
 }
 
-export function hasOwnProperty(target, property) {
+export function hasOwnProperty(target: object, property: string | symbol): boolean {
   return Object.hasOwnProperty.call(target, property);
 }
 
@@ -74,7 +80,7 @@ export function hasOwnProperty(target, property) {
  * @param string
  * @returns {*}
  */
-export function stripTrailingSlash(string) {
+export function stripTrailingSlash(string: any): any {
   if (!isString(string)) {
     return string;
   }
@@ -87,7 +93,7 @@ export const isAndroid = Platform.OS === 'android';
 
 export const isOther = Platform.OS !== 'ios' && Platform.OS !== 'android';
 
-export function tryJSONParse(string) {
+export function tryJSONParse(string: string | null | undefined): any {
   try {
     return string && JSON.parse(string);
   } catch (_) {
@@ -95,7 +101,7 @@ export function tryJSONParse(string) {
   }
 }
 
-export function tryJSONStringify(data) {
+export function tryJSONStringify(data: any): string | null {
   try {
     return JSON.stringify(data);
   } catch (_) {
@@ -103,14 +109,17 @@ export function tryJSONStringify(data) {
   }
 }
 
-export function parseListenerOrObserver(listenerOrObserver) {
+export function parseListenerOrObserver<T>(
+  listenerOrObserver: ((value: T) => void) | Observer<T>,
+): (value: T) => void {
   if (!isFunction(listenerOrObserver) && !isObject(listenerOrObserver)) {
+    throw new Error("'listenerOrObserver' expected a function or an object with 'next' function.");
   }
   if (isFunction(listenerOrObserver)) {
     return listenerOrObserver;
   }
-  if (isObject(listenerOrObserver) && isFunction(listenerOrObserver.next)) {
-    return listenerOrObserver.next.bind(listenerOrObserver);
+  if (isObject(listenerOrObserver) && isFunction((listenerOrObserver as Observer<T>).next)) {
+    return (listenerOrObserver as Observer<T>).next!.bind(listenerOrObserver);
   }
 
   throw new Error("'listenerOrObserver' expected a function or an object with 'next' function.");
@@ -119,7 +128,11 @@ export function parseListenerOrObserver(listenerOrObserver) {
 // Used to indicate if there is no corresponding modular function
 const NO_REPLACEMENT = true;
 
-const mapOfDeprecationReplacements = {
+type MethodMap = Record<string, string | typeof NO_REPLACEMENT>;
+type InstanceMap = Record<string, MethodMap>;
+type DeprecationMap = Record<string, InstanceMap>;
+
+const mapOfDeprecationReplacements: DeprecationMap = {
   analytics: {
     default: {
       logEvent: 'logEvent()',
@@ -523,12 +536,17 @@ const modularDeprecationMessage =
   'This method is deprecated (as well as all React Native Firebase namespaced API) and will be removed in the next major release ' +
   'as part of move to match Firebase Web modular SDK API. Please see migration guide for more details: https://rnfirebase.io/migrating-to-v22';
 
-export function deprecationConsoleWarning(nameSpace, methodName, instanceName, isModularMethod) {
+export function deprecationConsoleWarning(
+  nameSpace: string,
+  methodName: string,
+  instanceName: string,
+  isModularMethod: boolean,
+): void {
   if (!isModularMethod) {
     const moduleMap = mapOfDeprecationReplacements[nameSpace];
     if (moduleMap) {
       const instanceMap = moduleMap[instanceName];
-      const deprecatedMethod = instanceMap[methodName];
+      const deprecatedMethod = instanceMap?.[methodName];
       if (instanceMap && deprecatedMethod) {
         if (!globalThis.RNFB_SILENCE_MODULAR_DEPRECATION_WARNINGS) {
           // eslint-disable-next-line no-console
@@ -544,11 +562,11 @@ export function deprecationConsoleWarning(nameSpace, methodName, instanceName, i
 }
 
 export function createMessage(
-  nameSpace,
-  methodName,
-  instanceName = 'default',
-  uniqueMessage = null,
-) {
+  nameSpace: string,
+  methodName: string,
+  instanceName: string = 'default',
+  uniqueMessage: string | null = null,
+): string | undefined {
   if (uniqueMessage) {
     // Unique deprecation message used for testing
     return uniqueMessage;
@@ -570,9 +588,10 @@ export function createMessage(
       }
     }
   }
+  return undefined;
 }
 
-function getNamespace(target) {
+function getNamespace(target: any): string | undefined {
   if (target.constructor.name === 'DatabaseReference') {
     return 'database';
   }
@@ -588,13 +607,14 @@ function getNamespace(target) {
   }
   const className = target.name ? target.name : target.constructor.name;
   return Object.keys(mapOfDeprecationReplacements).find(key => {
-    if (mapOfDeprecationReplacements[key][className]) {
+    if (mapOfDeprecationReplacements[key]?.[className]) {
       return key;
     }
+    return false;
   });
 }
 
-function getInstanceName(target) {
+function getInstanceName(target: any): string {
   if (target.GeoPoint || target.CustomProvider) {
     // target is statics object. GeoPoint - Firestore, CustomProvider - AppCheck
     return 'statics';
@@ -619,13 +639,13 @@ function getInstanceName(target) {
   return target.constructor.name;
 }
 
-export function createDeprecationProxy(instance) {
+export function createDeprecationProxy<T extends object>(instance: T): T {
   return new Proxy(instance, {
-    construct(target, args) {
+    construct(target: any, args: any[]) {
       // needed for Timestamp which we pass as static, when we construct new instance, we need to wrap it in proxy again.
       return createDeprecationProxy(new target(...args));
     },
-    get(target, prop, receiver) {
+    get(target: any, prop: string | symbol, receiver: any) {
       const originalMethod = target[prop];
 
       if (prop === 'constructor') {
@@ -633,7 +653,7 @@ export function createDeprecationProxy(instance) {
       }
 
       if (target && target.constructor && target.constructor.name === 'FirestoreTimestamp') {
-        deprecationConsoleWarning('firestore', prop, 'FirestoreTimestamp', false);
+        deprecationConsoleWarning('firestore', prop as string, 'FirestoreTimestamp', false);
         return Reflect.get(target, prop, receiver);
       }
 
@@ -703,28 +723,30 @@ export function createDeprecationProxy(instance) {
         const instanceName = getInstanceName(target);
         const nameSpace = getNamespace(target);
 
-        if (descriptor.get) {
+        if (descriptor.get && nameSpace) {
           // Handle getter - call it and show deprecation warning
-          deprecationConsoleWarning(nameSpace, prop, instanceName, _isModularCall);
+          deprecationConsoleWarning(nameSpace, prop as string, instanceName, _isModularCall);
           return descriptor.get.call(target);
         }
 
-        if (descriptor.set) {
+        if (descriptor.set && nameSpace) {
           // Handle setter - return a function that calls the setter with deprecation warning
-          return function (value) {
-            deprecationConsoleWarning(nameSpace, prop, instanceName, _isModularCall);
-            descriptor.set.call(target, value);
+          return function (value: any) {
+            deprecationConsoleWarning(nameSpace, prop as string, instanceName, _isModularCall);
+            descriptor.set!.call(target, value);
           };
         }
       }
 
       if (typeof originalMethod === 'function') {
-        return function (...args) {
+        return function (...args: any[]) {
           const isModularMethod = args.includes(MODULAR_DEPRECATION_ARG);
           const instanceName = getInstanceName(target);
           const nameSpace = getNamespace(target);
 
-          deprecationConsoleWarning(nameSpace, prop, instanceName, isModularMethod);
+          if (nameSpace) {
+            deprecationConsoleWarning(nameSpace, prop as string, instanceName, isModularMethod);
+          }
 
           return originalMethod.apply(target, filterModularArgument(args));
         };
@@ -739,7 +761,7 @@ export const MODULAR_DEPRECATION_ARG = 'react-native-firebase-modular-method-cal
 // Flag to track if we're currently in a modular call
 let _isModularCall = false;
 
-export function withModularFlag(fn) {
+export function withModularFlag<T>(fn: () => T): T {
   const previousFlag = _isModularCall;
   _isModularCall = true;
   try {
@@ -749,11 +771,11 @@ export function withModularFlag(fn) {
   }
 }
 
-export function filterModularArgument(list) {
+export function filterModularArgument(list: any[]): any[] {
   return list.filter(arg => arg !== MODULAR_DEPRECATION_ARG);
 }
 
-export function warnIfNotModularCall(args, replacementMethodName = '') {
+export function warnIfNotModularCall(args: IArguments, replacementMethodName: string = ''): void {
   for (let i = 0; i < args.length; i++) {
     if (args[i] === MODULAR_DEPRECATION_ARG) {
       return;
diff --git a/packages/app/lib/common/path.js b/packages/app/lib/common/path.ts
similarity index 82%
rename from packages/app/lib/common/path.js
rename to packages/app/lib/common/path.ts
index 3e276f8529..89c0f70399 100644
--- a/packages/app/lib/common/path.js
+++ b/packages/app/lib/common/path.ts
@@ -18,7 +18,7 @@
 /**
  * Returns the next parent of the path e.g. /foo/bar/car -> /foo/bar
  */
-export function pathParent(path) {
+export function pathParent(path: string): string | null {
   if (path.length === 0) {
     return null;
   }
@@ -34,7 +34,7 @@ export function pathParent(path) {
 /**
  * Joins a parent and a child path
  */
-export function pathChild(path, childPath) {
+export function pathChild(path: string, childPath: string): string {
   const canonicalChildPath = pathPieces(childPath).join('/');
 
   if (path.length === 0) {
@@ -47,7 +47,7 @@ export function pathChild(path, childPath) {
 /**
  * Returns the last component of a path, e.g /foo/bar.jpeg -> bar.jpeg
  */
-export function pathLastComponent(path) {
+export function pathLastComponent(path: string): string {
   const index = path.lastIndexOf('/', path.length - 2);
   if (index === -1) {
     return path;
@@ -61,7 +61,7 @@ export function pathLastComponent(path) {
  * @param path
  * @returns {*}
  */
-export function pathPieces(path) {
+export function pathPieces(path: string): string[] {
   return path.split('/').filter($ => $.length > 0);
 }
 
@@ -70,7 +70,7 @@ export function pathPieces(path) {
  * @param path
  * @returns {boolean}
  */
-export function pathIsEmpty(path) {
+export function pathIsEmpty(path: string): boolean {
   return !pathPieces(path).length;
 }
 
@@ -79,7 +79,7 @@ export function pathIsEmpty(path) {
  * @param path
  * @returns {string|string}
  */
-export function pathToUrlEncodedString(path) {
+export function pathToUrlEncodedString(path: string): string {
   const pieces = pathPieces(path);
   let pathString = '';
   for (let i = 0; i < pieces.length; i++) {
@@ -95,7 +95,7 @@ export const INVALID_PATH_REGEX = /[[\].#$\u0000-\u001F\u007F]/;
  * @param path
  * @returns {boolean}
  */
-export function isValidPath(path) {
+export function isValidPath(path: unknown): boolean {
   return typeof path === 'string' && path.length !== 0 && !INVALID_PATH_REGEX.test(path);
 }
 
@@ -106,8 +106,8 @@ export const INVALID_KEY_REGEX = /[\[\].#$\/\u0000-\u001F\u007F]/;
  * @param key
  * @returns {boolean}
  */
-export function isValidKey(key) {
-  return typeof key === 'string' && key.length !== 0 && !INVALID_KEY_REGEX.test(path);
+export function isValidKey(key: unknown): boolean {
+  return typeof key === 'string' && key.length !== 0 && !INVALID_KEY_REGEX.test(key);
 }
 
 /**
@@ -115,7 +115,7 @@ export function isValidKey(key) {
  * @param path
  * @returns {*}
  */
-export function toFilePath(path) {
+export function toFilePath(path: string): string {
   let _filePath = path.replace('file://', '');
   if (_filePath.includes('%')) {
     _filePath = decodeURIComponent(_filePath);
diff --git a/packages/app/lib/common/promise.js b/packages/app/lib/common/promise.ts
similarity index 67%
rename from packages/app/lib/common/promise.js
rename to packages/app/lib/common/promise.ts
index b1f9b86e4d..40e1b53e78 100644
--- a/packages/app/lib/common/promise.js
+++ b/packages/app/lib/common/promise.ts
@@ -16,17 +16,19 @@
  */
 
 import { isFunction } from './validate';
+import type { Deferred, Callback } from '../types/internal';
 
 /**
- *
+ * Creates a deferred promise
  */
-export function promiseDefer() {
-  const deferred = {
+export function promiseDefer<T = void>(): Deferred<T> {
+  const deferred: Deferred<T> = {
+    promise: null as unknown as Promise<T>,
     resolve: null,
     reject: null,
   };
 
-  deferred.promise = new Promise((resolve, reject) => {
+  deferred.promise = new Promise<T>((resolve, reject) => {
     deferred.resolve = resolve;
     deferred.reject = reject;
   });
@@ -35,10 +37,14 @@ export function promiseDefer() {
 }
 
 /**
+ * Attaches an optional callback to a promise
  * @param promise
  * @param callback
  */
-export function promiseWithOptionalCallback(promise, callback) {
+export function promiseWithOptionalCallback<T>(
+  promise: Promise<T>,
+  callback?: Callback<T>,
+): Promise<T> {
   if (!isFunction(callback)) {
     return promise;
   }
@@ -46,9 +52,9 @@ export function promiseWithOptionalCallback(promise, callback) {
   return promise
     .then(result => {
       if (callback && callback.length === 1) {
-        callback(null);
+        (callback as (error: Error | null) => void)(null);
       } else if (callback) {
-        callback(null, result);
+        (callback as (error: Error | null, result?: T) => void)(null, result);
       }
 
       return result;
diff --git a/packages/app/lib/common/serialize.js b/packages/app/lib/common/serialize.ts
similarity index 86%
rename from packages/app/lib/common/serialize.js
rename to packages/app/lib/common/serialize.ts
index 2d92aecc73..f142f2552c 100644
--- a/packages/app/lib/common/serialize.js
+++ b/packages/app/lib/common/serialize.ts
@@ -17,8 +17,9 @@
 
 import { tryJSONParse, tryJSONStringify } from './index';
 import { isObject } from './validate';
+import type { SerializedValue } from '../types/internal';
 
-export function serializeType(value) {
+export function serializeType(value: any): SerializedValue {
   if (isObject(value)) {
     return {
       type: 'object',
@@ -32,7 +33,7 @@ export function serializeType(value) {
   };
 }
 
-export function serializeObject(object) {
+export function serializeObject(object: any): any {
   if (!isObject(object)) {
     return object;
   }
diff --git a/packages/app/lib/common/unitTestUtils.ts b/packages/app/lib/common/unitTestUtils.ts
index 5b764f5005..f2315f06f8 100644
--- a/packages/app/lib/common/unitTestUtils.ts
+++ b/packages/app/lib/common/unitTestUtils.ts
@@ -1,4 +1,3 @@
-// @ts-nocheck
 import { expect, jest } from '@jest/globals';
 import { createMessage } from './index';
 
@@ -28,10 +27,10 @@ export const createCheckV9Deprecation = (moduleNames: string[]): CheckV9Deprecat
     modularFunction: () => void,
     nonModularFunction: () => void,
     methodNameKey: string,
-    uniqueMessage: string?,
+    uniqueMessage?: string | null,
     checkFirebaseAppDeprecationWarning: boolean = false,
   ) => {
-    const moduleName = moduleNames[0]; // firestore, database, etc
+    const moduleName = moduleNames[0] as string; // firestore, database, etc
     const instanceName = moduleNames[1] || 'default'; // default, FirestoreCollectionReference, etc
     const consoleWarnSpy = jest.spyOn(console, 'warn');
     consoleWarnSpy.mockReset();
@@ -53,7 +52,9 @@ export const createCheckV9Deprecation = (moduleNames: string[]): CheckV9Deprecat
     consoleWarnSpy.mockRestore();
     const consoleWarnSpy2 = jest.spyOn(console, 'warn').mockImplementation(warnMessage => {
       const message = createMessage(moduleName, methodNameKey, instanceName, uniqueMessage);
-      expect(warnMessage).toMatch(message);
+      if (message) {
+        expect(warnMessage).toMatch(message);
+      }
     });
     nonModularFunction();
 
diff --git a/packages/app/lib/common/validate.js b/packages/app/lib/common/validate.ts
similarity index 68%
rename from packages/app/lib/common/validate.js
rename to packages/app/lib/common/validate.ts
index de974d40bc..00f8a268a5 100644
--- a/packages/app/lib/common/validate.js
+++ b/packages/app/lib/common/validate.ts
@@ -19,7 +19,10 @@ import { Platform } from 'react-native';
 
 const AlphaNumericUnderscore = /^[a-zA-Z0-9_]+$/;
 
-export function objectKeyValuesAreStrings(object) {
+/**
+ * Validates that all key-value pairs in an object are strings.
+ */
+export function objectKeyValuesAreStrings(object: unknown): boolean {
   if (!isObject(object)) {
     return false;
   }
@@ -27,7 +30,7 @@ export function objectKeyValuesAreStrings(object) {
   const entries = Object.entries(object);
 
   for (let i = 0; i < entries.length; i++) {
-    const [key, value] = entries[i];
+    const [key, value] = entries[i]!;
     if (!isString(key) || !isString(value)) {
       return false;
     }
@@ -42,7 +45,7 @@ export function objectKeyValuesAreStrings(object) {
  * @param value
  * @returns {boolean}
  */
-export function isNull(value) {
+export function isNull(value: unknown): value is null {
   return value === null;
 }
 
@@ -52,7 +55,7 @@ export function isNull(value) {
  * @param value
  * @returns {boolean}
  */
-export function isObject(value) {
+export function isObject(value: unknown): value is Record<string, unknown> {
   return value ? typeof value === 'object' && !Array.isArray(value) && !isNull(value) : false;
 }
 
@@ -62,9 +65,13 @@ export function isObject(value) {
  * @param value
  * @returns {boolean}
  */
-export function isDate(value) {
+export function isDate(value: unknown): value is Date {
   // use the global isNaN() and not Number.isNaN() since it will validate an Invalid Date
-  return value && Object.prototype.toString.call(value) === '[object Date]' && !isNaN(value);
+  return value &&
+    Object.prototype.toString.call(value) === '[object Date]' &&
+    !isNaN(value as number)
+    ? true
+    : false;
 }
 
 /**
@@ -73,7 +80,8 @@ export function isDate(value) {
  * @param value
  * @returns {*|boolean}
  */
-export function isFunction(value) {
+// eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
+export function isFunction(value: unknown): value is Function {
   return value ? typeof value === 'function' : false;
 }
 
@@ -82,7 +90,7 @@ export function isFunction(value) {
  * @param value
  * @return {boolean}
  */
-export function isString(value) {
+export function isString(value: unknown): value is string {
   return typeof value === 'string';
 }
 
@@ -91,7 +99,7 @@ export function isString(value) {
  * @param value
  * @return {boolean}
  */
-export function isNumber(value) {
+export function isNumber(value: unknown): value is number {
   return typeof value === 'number';
 }
 
@@ -100,7 +108,10 @@ export function isNumber(value) {
  * @param value
  * @return {boolean}
  */
-export function isE164PhoneNumber(value) {
+export function isE164PhoneNumber(value: unknown): boolean {
+  if (!isString(value)) {
+    return false;
+  }
   const PHONE_NUMBER = /^\+[1-9]\d{1,14}$/; // E.164
   return PHONE_NUMBER.test(value);
 }
@@ -110,7 +121,7 @@ export function isE164PhoneNumber(value) {
  * @param value
  * @returns {boolean}
  */
-export function isFinite(value) {
+export function isFinite(value: unknown): boolean {
   return Number.isFinite(value);
 }
 
@@ -119,7 +130,7 @@ export function isFinite(value) {
  * @param value
  * @returns {boolean}
  */
-export function isInteger(value) {
+export function isInteger(value: unknown): boolean {
   return Number.isInteger(value);
 }
 
@@ -129,16 +140,16 @@ export function isInteger(value) {
  * @param value
  * @return {boolean}
  */
-export function isBoolean(value) {
+export function isBoolean(value: unknown): value is boolean {
   return typeof value === 'boolean';
 }
 
 /**
  *
  * @param value
- * @returns {arg is Array<any>}
+ * @returns {arg is Array<unknown>}
  */
-export function isArray(value) {
+export function isArray(value: unknown): value is Array<unknown> {
   return Array.isArray(value);
 }
 
@@ -147,7 +158,7 @@ export function isArray(value) {
  * @param value
  * @returns {boolean}
  */
-export function isUndefined(value) {
+export function isUndefined(value: unknown): value is undefined {
   return typeof value === 'undefined';
 }
 
@@ -157,7 +168,10 @@ export function isUndefined(value) {
  * @param value
  * @returns {boolean}
  */
-export function isAlphaNumericUnderscore(value) {
+export function isAlphaNumericUnderscore(value: unknown): boolean {
+  if (!isString(value)) {
+    return false;
+  }
   return AlphaNumericUnderscore.test(value);
 }
 
@@ -167,7 +181,10 @@ export function isAlphaNumericUnderscore(value) {
  * @returns {boolean}
  */
 const IS_VALID_URL_REGEX = /^(http|https):\/\/[^ "]+$/;
-export function isValidUrl(url) {
+export function isValidUrl(url: unknown): boolean {
+  if (!isString(url)) {
+    return false;
+  }
   return IS_VALID_URL_REGEX.test(url);
 }
 
@@ -178,18 +195,22 @@ export function isValidUrl(url) {
  * @param oneOf
  * @returns {boolean}
  */
-export function isOneOf(value, oneOf = []) {
+export function isOneOf(value: unknown, oneOf: unknown[] = []): boolean {
   if (!isArray(oneOf)) {
     return false;
   }
   return oneOf.includes(value);
 }
 
-export function noop() {
+export function noop(): void {
   // noop-🐈
 }
 
-export function validateOptionalNativeDependencyExists(firebaseJsonKey, apiName, nativeFnExists) {
+export function validateOptionalNativeDependencyExists(
+  firebaseJsonKey: string,
+  apiName: string,
+  nativeFnExists: boolean,
+): void {
   if (nativeFnExists) {
     return;
   }
diff --git a/packages/app/lib/index.ts b/packages/app/lib/index.ts
new file mode 100644
index 0000000000..131ad4a115
--- /dev/null
+++ b/packages/app/lib/index.ts
@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+export { firebase, utils, default } from './namespaced';
+export * from './modular';
+export type {
+  ReactNativeFirebase,
+  Utils,
+  FirebaseApp,
+  LogCallbackParams,
+  LogCallback,
+  LogOptions,
+} from './types/app';
diff --git a/packages/app/lib/internal/FirebaseModule.js b/packages/app/lib/internal/FirebaseModule.js
deleted file mode 100644
index b970643b5c..0000000000
--- a/packages/app/lib/internal/FirebaseModule.js
+++ /dev/null
@@ -1,62 +0,0 @@
-/*
- * Copyright (c) 2016-present Invertase Limited & Contributors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this library except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-import { getAppModule, getNativeModule } from './registry/nativeModule';
-import SharedEventEmitter from './SharedEventEmitter';
-
-let firebaseJson = null;
-
-export default class FirebaseModule {
-  constructor(app, config, customUrlOrRegion) {
-    this._app = app;
-    this._nativeModule = null;
-    this._customUrlOrRegion = customUrlOrRegion;
-    this._config = Object.assign({}, config);
-  }
-
-  get app() {
-    return this._app;
-  }
-
-  get firebaseJson() {
-    if (firebaseJson) {
-      return firebaseJson;
-    }
-    firebaseJson = JSON.parse(getAppModule().FIREBASE_RAW_JSON);
-    return firebaseJson;
-  }
-
-  get emitter() {
-    return SharedEventEmitter;
-  }
-
-  // TODO Handle custom url or region?
-  eventNameForApp(...args) {
-    return `${this.app.name}-${args.join('-')}`;
-  }
-
-  get native() {
-    if (this._nativeModule) {
-      return this._nativeModule;
-    }
-    this._nativeModule = getNativeModule(this);
-    return this._nativeModule;
-  }
-}
-
-// Instance of checks don't work once compiled
-FirebaseModule.__extended__ = {};
diff --git a/packages/app/lib/internal/FirebaseModule.ts b/packages/app/lib/internal/FirebaseModule.ts
new file mode 100644
index 0000000000..c799aecb81
--- /dev/null
+++ b/packages/app/lib/internal/FirebaseModule.ts
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import { getAppModule, getNativeModule } from './registry/nativeModule';
+import SharedEventEmitter from './SharedEventEmitter';
+import type { ReactNativeFirebase } from '../types/app';
+import type { FirebaseJsonConfig, ModuleConfig } from '../types/internal';
+import type { ReactNativeFirebaseNativeModules } from './NativeModules';
+import type EventEmitter from 'react-native/Libraries/vendor/emitter/EventEmitter';
+
+let firebaseJson: FirebaseJsonConfig | null = null;
+
+export default class FirebaseModule<
+  NativeModuleName extends keyof ReactNativeFirebaseNativeModules = any,
+> {
+  _app: ReactNativeFirebase.FirebaseAppBase;
+  _nativeModule: ReactNativeFirebaseNativeModules[NativeModuleName] | null;
+  _customUrlOrRegion: string | null;
+  _config: ModuleConfig;
+
+  constructor(
+    app: ReactNativeFirebase.FirebaseAppBase,
+    config: ModuleConfig,
+    customUrlOrRegion?: string | null,
+  ) {
+    this._app = app;
+    this._nativeModule = null;
+    this._customUrlOrRegion = customUrlOrRegion || null;
+    this._config = Object.assign({}, config);
+  }
+
+  get app(): ReactNativeFirebase.FirebaseApp {
+    return this._app as unknown as ReactNativeFirebase.FirebaseApp;
+  }
+
+  get firebaseJson(): FirebaseJsonConfig {
+    if (firebaseJson) {
+      return firebaseJson;
+    }
+    firebaseJson = JSON.parse(getAppModule().FIREBASE_RAW_JSON);
+    return firebaseJson as FirebaseJsonConfig;
+  }
+
+  get emitter(): EventEmitter {
+    return SharedEventEmitter;
+  }
+
+  eventNameForApp(...args: Array<string | number>): string {
+    return `${this.app.name}-${args.join('-')}`;
+  }
+
+  get native(): ReactNativeFirebaseNativeModules[NativeModuleName] {
+    if (this._nativeModule) {
+      return this._nativeModule;
+    }
+    this._nativeModule = getNativeModule(
+      this,
+    ) as unknown as ReactNativeFirebaseNativeModules[NativeModuleName];
+    return this._nativeModule;
+  }
+}
+
+// Instance of checks don't work once compiled
+(FirebaseModule as any).__extended__ = {};
diff --git a/packages/app/lib/internal/NativeFirebaseError.js b/packages/app/lib/internal/NativeFirebaseError.ts
similarity index 75%
rename from packages/app/lib/internal/NativeFirebaseError.js
rename to packages/app/lib/internal/NativeFirebaseError.ts
index 5fed6889ba..66a9b1c4ee 100644
--- a/packages/app/lib/internal/NativeFirebaseError.js
+++ b/packages/app/lib/internal/NativeFirebaseError.ts
@@ -15,12 +15,31 @@
  *
  */
 
+import type { NativeErrorUserInfo, NativeError } from '../types/internal';
+
 export default class NativeFirebaseError extends Error {
-  static fromEvent(errorEvent, namespace, stack) {
-    return new NativeFirebaseError({ userInfo: errorEvent }, stack || new Error().stack, namespace);
+  readonly namespace!: string;
+  readonly code!: string;
+  readonly jsStack!: string;
+  readonly userInfo!: NativeErrorUserInfo;
+  readonly customData: any;
+  readonly operationType!: string | null;
+  readonly nativeErrorCode!: string | number | null;
+  readonly nativeErrorMessage!: string | null;
+
+  static fromEvent(
+    errorEvent: NativeErrorUserInfo,
+    namespace: string,
+    stack?: string,
+  ): NativeFirebaseError {
+    return new NativeFirebaseError(
+      { userInfo: errorEvent },
+      stack || new Error().stack!,
+      namespace,
+    );
   }
 
-  constructor(nativeError, jsStack, namespace) {
+  constructor(nativeError: NativeError, jsStack: string, namespace: string) {
     super();
     const { userInfo } = nativeError;
 
@@ -86,7 +105,7 @@ export default class NativeFirebaseError extends Error {
    *
    * @returns {string}
    */
-  static getStackWithMessage(message, jsStack) {
+  static getStackWithMessage(message: string, jsStack: string): string {
     return [message, ...jsStack.split('\n').slice(2, 13)].join('\n');
   }
 }
diff --git a/packages/app/lib/internal/NativeModules.ts b/packages/app/lib/internal/NativeModules.ts
new file mode 100644
index 0000000000..3700721c2d
--- /dev/null
+++ b/packages/app/lib/internal/NativeModules.ts
@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import type { ReactNativeFirebase } from '../types/app';
+
+/**
+ * Base type for all React Native Firebase native modules.
+ * Each package can extend this interface via module augmentation to add their own native methods.
+ */
+// eslint-disable-next-line @typescript-eslint/no-empty-object-type
+export interface ReactNativeFirebaseNativeModules {
+  // Base interface - packages will augment this
+}
+
+/**
+ * Interface for wrapped native modules returned by getAppModule() and getNativeModule()
+ * This represents the native module after wrapping with error handling
+ */
+export interface WrappedNativeModule {
+  [key: string]: unknown;
+}
+
+/**
+ * App Module native methods that are always available
+ */
+export interface RNFBAppModuleInterface {
+  // Constants
+  NATIVE_FIREBASE_APPS: Array<{
+    appConfig: ReactNativeFirebase.FirebaseAppConfig;
+    options: ReactNativeFirebase.FirebaseAppOptions;
+  }>;
+  FIREBASE_RAW_JSON: string;
+
+  // Methods
+  initializeApp(
+    options: ReactNativeFirebase.FirebaseAppOptions,
+    appConfig: ReactNativeFirebase.FirebaseAppConfig,
+  ): Promise<void>;
+  deleteApp(name: string): Promise<void>;
+  setLogLevel(logLevel: string): void;
+  metaGetAll(): Promise<{ [key: string]: string | boolean }>;
+  jsonGetAll(): Promise<{ [key: string]: string | boolean }>;
+  preferencesClearAll(): Promise<void>;
+  preferencesGetAll(): Promise<{ [key: string]: string | boolean }>;
+  preferencesSetBool(key: string, value: boolean): Promise<void>;
+  preferencesSetString(key: string, value: string): Promise<void>;
+  setAutomaticDataCollectionEnabled(name: string, enabled: boolean): void;
+
+  // Event emitter methods
+  eventsNotifyReady(ready: boolean): void;
+  eventsAddListener(eventType: string): void;
+  eventsRemoveListener(eventType: string, removeAll: boolean): void;
+
+  // React Native EventEmitter compatibility
+  addListener?: (eventName: string) => void;
+  removeListeners?: (count: number) => void;
+}
+
+/**
+ * Utils Module native methods (from the app package)
+ */
+export interface RNFBUtilsModuleInterface {
+  // Android-only properties and methods
+  isRunningInTestLab: boolean;
+  androidPlayServices: {
+    isAvailable: boolean;
+    status: number;
+    hasResolution: boolean;
+    isUserResolvableError: boolean;
+    error: string | undefined;
+  };
+  androidGetPlayServicesStatus(): Promise<{
+    isAvailable: boolean;
+    status: number;
+    hasResolution: boolean;
+    isUserResolvableError: boolean;
+    error: string | undefined;
+  }>;
+  androidPromptForPlayServices(): Promise<void>;
+  androidMakePlayServicesAvailable(): Promise<void>;
+  androidResolutionForPlayServices(): Promise<void>;
+}
+
+// Augment the base interface with app package's native modules
+declare module './NativeModules' {
+  interface ReactNativeFirebaseNativeModules {
+    RNFBUtilsModule: RNFBUtilsModuleInterface;
+    RNFBAppModule: RNFBAppModuleInterface;
+  }
+}
+
+/**
+ * Helper type to get a specific native module type by name
+ */
+export type GetNativeModule<T extends keyof ReactNativeFirebaseNativeModules> =
+  ReactNativeFirebaseNativeModules[T];
+
+/**
+ * Union type of all available native module types
+ */
+export type AnyNativeModule =
+  ReactNativeFirebaseNativeModules[keyof ReactNativeFirebaseNativeModules];
diff --git a/packages/app/lib/internal/RNFBNativeEventEmitter.js b/packages/app/lib/internal/RNFBNativeEventEmitter.ts
similarity index 57%
rename from packages/app/lib/internal/RNFBNativeEventEmitter.js
rename to packages/app/lib/internal/RNFBNativeEventEmitter.ts
index 2c13e90ab0..2abb338595 100644
--- a/packages/app/lib/internal/RNFBNativeEventEmitter.js
+++ b/packages/app/lib/internal/RNFBNativeEventEmitter.ts
@@ -15,10 +15,28 @@
  *
  */
 
-import { NativeEventEmitter } from 'react-native';
+import { type EmitterSubscription, NativeEventEmitter } from 'react-native';
 import { getReactNativeModule } from './nativeModule';
+import type { RNFBAppModuleInterface } from './NativeModules';
+
+/**
+ * Type for the eventsNotifyReady native method
+ */
+type EventsNotifyReadyMethod = (ready: boolean) => void;
+
+/**
+ * Type for the eventsAddListener native method
+ */
+type EventsAddListenerMethod = (eventType: string) => void;
+
+/**
+ * Type for the eventsRemoveListener native method
+ */
+type EventsRemoveListenerMethod = (eventType: string, removeAll: boolean) => void;
 
 class RNFBNativeEventEmitter extends NativeEventEmitter {
+  ready: boolean;
+
   constructor() {
     const RNFBAppModule = getReactNativeModule('RNFBAppModule');
     if (!RNFBAppModule) {
@@ -26,22 +44,29 @@ class RNFBNativeEventEmitter extends NativeEventEmitter {
         'Native module RNFBAppModule not found. Re-check module install, linking, configuration, build and install steps.',
       );
     }
-    super(RNFBAppModule);
+    // Cast to any for NativeEventEmitter constructor which expects React Native's NativeModule type
+    super(RNFBAppModule as any);
     this.ready = false;
   }
 
-  addListener(eventType, listener, context) {
-    const RNFBAppModule = getReactNativeModule('RNFBAppModule');
+  addListener(
+    eventType: string,
+    listener: (...args: unknown[]) => unknown,
+    context?: object,
+  ): EmitterSubscription {
+    const RNFBAppModule = getReactNativeModule(
+      'RNFBAppModule',
+    ) as unknown as RNFBAppModuleInterface;
     if (!this.ready) {
-      RNFBAppModule.eventsNotifyReady(true);
+      (RNFBAppModule.eventsNotifyReady as EventsNotifyReadyMethod)(true);
       this.ready = true;
     }
-    RNFBAppModule.eventsAddListener(eventType);
+    (RNFBAppModule.eventsAddListener as EventsAddListenerMethod)(eventType);
     if (globalThis.RNFBDebug) {
       // eslint-disable-next-line no-console
       console.debug(`[RNFB-->Event][👂] ${eventType} -> listening`);
     }
-    const listenerDebugger = (...args) => {
+    const listenerDebugger = (...args: unknown[]) => {
       if (globalThis.RNFBDebug) {
         // eslint-disable-next-line no-console
         console.debug(`[RNFB<--Event][📣] ${eventType} <-`, JSON.stringify(args[0]));
@@ -68,16 +93,18 @@ class RNFBNativeEventEmitter extends NativeEventEmitter {
     // - addListener returns an unsubscriber instead of a more complex object with eventType etc
 
     // make sure eventType for backwards compatibility just in case
-    subscription.eventType = `rnfb_${eventType}`;
+    (subscription as any).eventType = `rnfb_${eventType}`;
 
     // New style is to return a remove function on the object, just in case people call that,
     // we will modify it to do our native unsubscription then call the original
-    let originalRemove = subscription.remove;
-    let newRemove = () => {
-      RNFBAppModule.eventsRemoveListener(eventType, false);
-      if (super.removeSubscription != null) {
+    const originalRemove = subscription.remove;
+    const newRemove = () => {
+      const module = getReactNativeModule('RNFBAppModule') as unknown as RNFBAppModuleInterface;
+      (module.eventsRemoveListener as EventsRemoveListenerMethod)(eventType, false);
+      const superClass = Object.getPrototypeOf(Object.getPrototypeOf(this));
+      if (superClass.removeSubscription != null) {
         // This is for RN <= 0.64 - 65 and greater no longer have removeSubscription
-        super.removeSubscription(subscription);
+        superClass.removeSubscription(subscription);
       } else if (originalRemove != null) {
         // This is for RN >= 0.65
         originalRemove();
@@ -87,18 +114,24 @@ class RNFBNativeEventEmitter extends NativeEventEmitter {
     return subscription;
   }
 
-  removeAllListeners(eventType) {
-    const RNFBAppModule = getReactNativeModule('RNFBAppModule');
-    RNFBAppModule.eventsRemoveListener(eventType, true);
+  removeAllListeners(eventType: string): void {
+    const RNFBAppModule = getReactNativeModule(
+      'RNFBAppModule',
+    ) as unknown as RNFBAppModuleInterface;
+    (RNFBAppModule.eventsRemoveListener as EventsRemoveListenerMethod)(eventType, true);
     super.removeAllListeners(`rnfb_${eventType}`);
   }
 
   // This is likely no longer ever called, but it is here for backwards compatibility with RN <= 0.64
-  removeSubscription(subscription) {
-    const RNFBAppModule = getReactNativeModule('RNFBAppModule');
-    RNFBAppModule.eventsRemoveListener(subscription.eventType.replace('rnfb_'), false);
-    if (super.removeSubscription) {
-      super.removeSubscription(subscription);
+  removeSubscription(subscription: EmitterSubscription & { eventType?: string }): void {
+    const RNFBAppModule = getReactNativeModule(
+      'RNFBAppModule',
+    ) as unknown as RNFBAppModuleInterface;
+    const eventType = subscription.eventType?.replace('rnfb_', '') || '';
+    (RNFBAppModule.eventsRemoveListener as EventsRemoveListenerMethod)(eventType, false);
+    const superClass = Object.getPrototypeOf(Object.getPrototypeOf(this));
+    if (superClass.removeSubscription) {
+      superClass.removeSubscription(subscription);
     }
   }
 }
diff --git a/packages/app/lib/internal/SharedEventEmitter.js b/packages/app/lib/internal/SharedEventEmitter.ts
similarity index 100%
rename from packages/app/lib/internal/SharedEventEmitter.js
rename to packages/app/lib/internal/SharedEventEmitter.ts
diff --git a/packages/app/lib/internal/asyncStorage.js b/packages/app/lib/internal/asyncStorage.js
deleted file mode 100644
index 3cd4448531..0000000000
--- a/packages/app/lib/internal/asyncStorage.js
+++ /dev/null
@@ -1,47 +0,0 @@
-export const memoryStorage = new Map();
-
-export const prefix = '@react-native-firebase:';
-
-const asyncStorageMemory = {
-  setItem(key, value) {
-    memoryStorage.set(key, value);
-    return Promise.resolve();
-  },
-  getItem(key) {
-    const hasValue = memoryStorage.has(key);
-    if (hasValue) {
-      return Promise.resolve(memoryStorage.get(key));
-    }
-    return Promise.resolve(null);
-  },
-  removeItem: function (key) {
-    memoryStorage.delete(key);
-    return Promise.resolve();
-  },
-};
-
-let asyncStorage = asyncStorageMemory;
-
-export async function getReactNativeAsyncStorageInternal() {
-  return asyncStorage;
-}
-
-export function setReactNativeAsyncStorageInternal(asyncStorageInstance) {
-  asyncStorage = asyncStorageInstance || asyncStorageMemory;
-}
-
-export function isMemoryStorage() {
-  return asyncStorage === asyncStorageMemory;
-}
-
-export async function setItem(key, value) {
-  return await asyncStorage.setItem(prefix + key, value);
-}
-
-export async function getItem(key) {
-  return await asyncStorage.getItem(prefix + key);
-}
-
-export async function removeItem(key) {
-  return await asyncStorage.removeItem(prefix + key);
-}
diff --git a/packages/app/lib/internal/asyncStorage.ts b/packages/app/lib/internal/asyncStorage.ts
new file mode 100644
index 0000000000..6b87420060
--- /dev/null
+++ b/packages/app/lib/internal/asyncStorage.ts
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import type { AsyncStorageStatic } from '../types/internal';
+
+// Memory storage Map instance
+export const memoryStorage = new Map<string, string>();
+
+// Storage key prefix
+export const prefix = '@react-native-firebase:';
+
+const asyncStorageMemory: AsyncStorageStatic = {
+  setItem(key: string, value: string): Promise<void> {
+    memoryStorage.set(key, value);
+    return Promise.resolve();
+  },
+  getItem(key: string): Promise<string | null> {
+    const hasValue = memoryStorage.has(key);
+    if (hasValue) {
+      return Promise.resolve(memoryStorage.get(key) || null);
+    }
+    return Promise.resolve(null);
+  },
+  removeItem(key: string): Promise<void> {
+    memoryStorage.delete(key);
+    return Promise.resolve();
+  },
+};
+
+let asyncStorage: AsyncStorageStatic = asyncStorageMemory;
+
+// Get the current AsyncStorage instance (either React Native AsyncStorage or memory storage)
+export async function getReactNativeAsyncStorageInternal(): Promise<AsyncStorageStatic> {
+  return asyncStorage;
+}
+
+// Set the AsyncStorage instance to use (React Native AsyncStorage or fallback to memory storage)
+export function setReactNativeAsyncStorageInternal(
+  asyncStorageInstance?: AsyncStorageStatic,
+): void {
+  asyncStorage = asyncStorageInstance || asyncStorageMemory;
+}
+
+// Check if currently using memory storage (fallback)
+export function isMemoryStorage(): boolean {
+  return asyncStorage === asyncStorageMemory;
+}
+
+// Set an item in storage with the React Native Firebase prefix
+export async function setItem(key: string, value: string): Promise<void> {
+  return await asyncStorage.setItem(prefix + key, value);
+}
+
+// Get an item from storage with the React Native Firebase prefix
+export async function getItem(key: string): Promise<string | null> {
+  return await asyncStorage.getItem(prefix + key);
+}
+
+// Remove an item from storage with the React Native Firebase prefix
+export async function removeItem(key: string): Promise<void> {
+  return await asyncStorage.removeItem(prefix + key);
+}
diff --git a/packages/app/lib/internal/constants.js b/packages/app/lib/internal/constants.ts
similarity index 93%
rename from packages/app/lib/internal/constants.js
rename to packages/app/lib/internal/constants.ts
index 642ef31c92..4741b11345 100644
--- a/packages/app/lib/internal/constants.js
+++ b/packages/app/lib/internal/constants.ts
@@ -39,4 +39,6 @@ export const KNOWN_NAMESPACES = [
   'notifications',
   'perf',
   'utils',
-];
+] as const;
+
+export type KnownNamespace = (typeof KNOWN_NAMESPACES)[number];
diff --git a/packages/app/lib/internal/global.d.ts b/packages/app/lib/internal/global.d.ts
new file mode 100644
index 0000000000..7112dd20c0
--- /dev/null
+++ b/packages/app/lib/internal/global.d.ts
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+/**
+ * Global RNFB properties for debugging and testing
+ */
+declare global {
+  // Debug and testing flags
+  var RNFBDebug: boolean | undefined;
+  var RNFBTest: boolean | undefined;
+  var RNFBDebugInTestLeakDetection: boolean | undefined;
+  var RNFBDebugLastTest: string | undefined;
+
+  // Modular API deprecation flags
+  var RNFB_SILENCE_MODULAR_DEPRECATION_WARNINGS: boolean | undefined;
+  var RNFB_MODULAR_DEPRECATION_STRICT_MODE: boolean | undefined;
+}
+
+export {};
diff --git a/packages/app/lib/internal/index.js b/packages/app/lib/internal/index.ts
similarity index 97%
rename from packages/app/lib/internal/index.js
rename to packages/app/lib/internal/index.ts
index 120bea13b6..4774df70c0 100644
--- a/packages/app/lib/internal/index.js
+++ b/packages/app/lib/internal/index.ts
@@ -19,6 +19,7 @@ export { default as FirebaseApp } from '../FirebaseApp';
 export * from './constants';
 export { default as FirebaseModule } from './FirebaseModule';
 export { default as NativeFirebaseError } from './NativeFirebaseError';
+export * from './NativeModules';
 export * from './registry/app';
 export * from './registry/namespace';
 export * from './registry/nativeModule';
diff --git a/packages/app/lib/internal/logger.d.ts b/packages/app/lib/internal/logger.d.ts
deleted file mode 100644
index e48f506274..0000000000
--- a/packages/app/lib/internal/logger.d.ts
+++ /dev/null
@@ -1,85 +0,0 @@
-export type LogLevelString = 'debug' | 'verbose' | 'info' | 'warn' | 'error' | 'silent';
-
-export interface LogOptions {
-  level: LogLevelString;
-}
-
-export type LogCallback = (callbackParams: LogCallbackParams) => void;
-
-export interface LogCallbackParams {
-  level: LogLevelString;
-  message: string;
-  args: unknown[];
-  type: string;
-}
-
-/**
- * A container for all of the Logger instances
- */
-export const instances: Logger[] = [];
-
-/**
- * The JS SDK supports 5 log levels and also allows a user the ability to
- * silence the logs altogether.
- *
- * The order is a follows:
- * DEBUG < VERBOSE < INFO < WARN < ERROR
- *
- * All of the log types above the current log level will be captured (i.e. if
- * you set the log level to `INFO`, errors will still be logged, but `DEBUG` and
- * `VERBOSE` logs will not)
- */
-export enum LogLevel {
-  DEBUG,
-  VERBOSE,
-  INFO,
-  WARN,
-  ERROR,
-  SILENT,
-}
-
-type LevelStringToEnum = {
-  debug: LogLevel.DEBUG;
-  verbose: LogLevel.VERBOSE;
-  info: LogLevel.INFO;
-  warn: LogLevel.WARN;
-  error: LogLevel.ERROR;
-  silent: LogLevel.SILENT;
-};
-
-/**
- * The default log level
- */
-type DefaultLogLevel = LogLevel.INFO;
-
-/**
- * We allow users the ability to pass their own log handler. We will pass the
- * type of log, the current log level, and any other arguments passed (i.e. the
- * messages that the user wants to log) to this function.
- */
-export type LogHandler = (loggerInstance: Logger, logType: LogLevel, ...args: unknown[]) => void;
-
-export class Logger {
-  constructor(name: string);
-
-  get logLevel(): LogLevel;
-  set logLevel(val: LogLevel);
-
-  setLogLevel(val: LogLevel | LogLevelString): void;
-
-  get logHandler(): LogHandler;
-  set logHandler(val: LogHandler);
-
-  get userLogHandler(): LogHandler | null;
-  set userLogHandler(val: LogHandler | null);
-
-  debug(...args: unknown[]): void;
-  log(...args: unknown[]): void;
-  info(...args: unknown[]): void;
-  warn(...args: unknown[]): void;
-  error(...args: unknown[]): void;
-}
-
-export const setLogLevel: (level: LogLevelString | LogLevel) => void;
-
-export const setUserLogHandler: (logCallback: LogCallback | null, options?: LogOptions) => void;
diff --git a/packages/app/lib/internal/logger.js b/packages/app/lib/internal/logger.ts
similarity index 62%
rename from packages/app/lib/internal/logger.js
rename to packages/app/lib/internal/logger.ts
index b1b84ace55..fac92d7a9c 100644
--- a/packages/app/lib/internal/logger.js
+++ b/packages/app/lib/internal/logger.ts
@@ -15,37 +15,48 @@
  *
  */
 
+import type { LogCallback, LogOptions } from '../types/app';
+
+type LogLevelString = 'debug' | 'verbose' | 'info' | 'warn' | 'error' | 'silent';
+
 /**
- * @typedef {import('./logger').Logger} Logger
- * @typedef {import('./logger').setLogLevel} setLogLevel
- * @typedef {import('./logger').setUserLogHandler} setUserLogHandler
- * @typedef {import('./logger').LogHandler} LogHandler
- * @typedef {import('./logger').LogLevel} LogLevel
- * @typedef {import('./logger').LevelStringToEnum} LevelStringToEnum
- * @typedef {import('./logger').DefaultLogLevel} DefaultLogLevel
+ * The JS SDK supports 5 log levels and also allows a user the ability to
+ * silence the logs altogether.
+ *
+ * The order is a follows:
+ * DEBUG < VERBOSE < INFO < WARN < ERROR
+ *
+ * All of the log types above the current log level will be captured (i.e. if
+ * you set the log level to `INFO`, errors will still be logged, but `DEBUG` and
+ * `VERBOSE` logs will not)
  */
-
-const LogLevel = {
-  DEBUG: 0,
-  VERBOSE: 1,
-  INFO: 2,
-  WARN: 3,
-  ERROR: 4,
-  SILENT: 5,
-};
+export enum LogLevel {
+  DEBUG = 0,
+  VERBOSE = 1,
+  INFO = 2,
+  WARN = 3,
+  ERROR = 4,
+  SILENT = 5,
+}
 
 // mimic the LogLevel in firebase-js-sdk TS
-const reverseLogLevel = obj => {
-  const reversed = {};
+const reverseLogLevel = (obj: typeof LogLevel): Record<number, string> => {
+  const reversed: Record<number, string> = {};
   for (const [key, value] of Object.entries(obj)) {
-    reversed[value] = key;
+    if (typeof value === 'number') {
+      reversed[value] = key;
+    }
   }
   return reversed;
 };
 
 const LogLevelReversed = reverseLogLevel(LogLevel);
 
-const levelStringToEnum = {
+type LevelStringToEnum = {
+  [K in LogLevelString]: LogLevel;
+};
+
+const levelStringToEnum: LevelStringToEnum = {
   debug: LogLevel.DEBUG,
   verbose: LogLevel.VERBOSE,
   info: LogLevel.INFO,
@@ -60,21 +71,28 @@ const levelStringToEnum = {
  * (i.e. once for firebase, and once in the console), we are sending `DEBUG`
  * logs to the `console.log` function.
  */
-const ConsoleMethod = {
+const ConsoleMethod: Record<LogLevel, 'log' | 'info' | 'warn' | 'error'> = {
   [LogLevel.DEBUG]: 'log',
   [LogLevel.VERBOSE]: 'log',
   [LogLevel.INFO]: 'info',
   [LogLevel.WARN]: 'warn',
   [LogLevel.ERROR]: 'error',
+  [LogLevel.SILENT]: 'error', // fallback, should never be used
 };
 
+/**
+ * We allow users the ability to pass their own log handler. We will pass the
+ * type of log, the current log level, and any other arguments passed (i.e. the
+ * messages that the user wants to log) to this function.
+ */
+export type LogHandler = (loggerInstance: Logger, logType: LogLevel, ...args: unknown[]) => void;
+
 /**
  * The default log handler will forward DEBUG, VERBOSE, INFO, WARN, and ERROR
  * messages on to their corresponding console counterparts (if the log method
  * is supported by the current log level)
- * @type {LogHandler}
  */
-const defaultLogHandler = (instance, logType, ...args) => {
+const defaultLogHandler: LogHandler = (instance, logType, ...args) => {
   if (logType < instance.logLevel) {
     return;
   }
@@ -82,8 +100,7 @@ const defaultLogHandler = (instance, logType, ...args) => {
   const method = ConsoleMethod[logType];
   if (method) {
     // 'log' | 'info' | 'warn' | 'error'
-    // eslint-disable-next-line no-console
-    console[method](`[${now}]  ${instance.name}:`, ...args);
+    (console as any)[method](`[${now}]  ${instance.name}:`, ...args);
   } else {
     throw new Error(`Attempted to log a message with an invalid logType (value: ${logType})`);
   }
@@ -91,20 +108,27 @@ const defaultLogHandler = (instance, logType, ...args) => {
 
 const defaultLogLevel = LogLevel.INFO;
 
-export const instances = [];
-
 /**
- * @type {Logger}
+ * A container for all of the Logger instances
  */
+export const instances: Logger[] = [];
 
+/**
+ * Logger class for Firebase
+ */
 export class Logger {
+  name: string;
+  private _logLevel: LogLevel = defaultLogLevel;
+  private _logHandler: LogHandler = defaultLogHandler;
+  private _userLogHandler: LogHandler | null = null;
+
   /**
    * Gives you an instance of a Logger to capture messages according to
    * Firebase's logging scheme.
    *
    * @param name The name that the logs will be associated with
    */
-  constructor(name) {
+  constructor(name: string) {
     /**
      * Capture the current instance for later use
      */
@@ -115,13 +139,11 @@ export class Logger {
   /**
    * The log level of the given Logger instance.
    */
-  _logLevel = defaultLogLevel;
-
-  get logLevel() {
+  get logLevel(): LogLevel {
     return this._logLevel;
   }
 
-  set logLevel(val) {
+  set logLevel(val: LogLevel) {
     if (!(val in LogLevel)) {
       throw new TypeError(`Invalid value "${val}" assigned to \`logLevel\``);
     }
@@ -129,7 +151,7 @@ export class Logger {
   }
 
   // Workaround for setter/getter having to be the same type.
-  setLogLevel(val) {
+  setLogLevel(val: LogLevel | LogLevelString): void {
     this._logLevel = typeof val === 'string' ? levelStringToEnum[val] : val;
   }
 
@@ -137,11 +159,11 @@ export class Logger {
    * The main (internal) log handler for the Logger instance.
    * Can be set to a new function in internal package code but not by user.
    */
-  _logHandler = defaultLogHandler;
-  get logHandler() {
+  get logHandler(): LogHandler {
     return this._logHandler;
   }
-  set logHandler(val) {
+
+  set logHandler(val: LogHandler) {
     if (typeof val !== 'function') {
       throw new TypeError('Value assigned to `logHandler` must be a function');
     }
@@ -151,11 +173,11 @@ export class Logger {
   /**
    * The optional, additional, user-defined log handler for the Logger instance.
    */
-  _userLogHandler = null;
-  get userLogHandler() {
+  get userLogHandler(): LogHandler | null {
     return this._userLogHandler;
   }
-  set userLogHandler(val) {
+
+  set userLogHandler(val: LogHandler | null) {
     this._userLogHandler = val;
   }
 
@@ -163,50 +185,57 @@ export class Logger {
    * The functions below are all based on the `console` interface
    */
 
-  debug(...args) {
+  debug(...args: unknown[]): void {
     this._userLogHandler && this._userLogHandler(this, LogLevel.DEBUG, ...args);
     this._logHandler(this, LogLevel.DEBUG, ...args);
   }
-  log(...args) {
+
+  log(...args: unknown[]): void {
     this._userLogHandler && this._userLogHandler(this, LogLevel.VERBOSE, ...args);
     this._logHandler(this, LogLevel.VERBOSE, ...args);
   }
-  info(...args) {
+
+  info(...args: unknown[]): void {
     this._userLogHandler && this._userLogHandler(this, LogLevel.INFO, ...args);
     this._logHandler(this, LogLevel.INFO, ...args);
   }
-  warn(...args) {
+
+  warn(...args: unknown[]): void {
     this._userLogHandler && this._userLogHandler(this, LogLevel.WARN, ...args);
     this._logHandler(this, LogLevel.WARN, ...args);
   }
-  error(...args) {
+
+  error(...args: unknown[]): void {
     this._userLogHandler && this._userLogHandler(this, LogLevel.ERROR, ...args);
     this._logHandler(this, LogLevel.ERROR, ...args);
   }
 }
 
 /**
- * @type {setLogLevel}
+ * Sets the log level for all Logger instances
  */
-export function setLogLevelInternal(level) {
+export function setLogLevel(level: LogLevelString | LogLevel): void {
   instances.forEach(inst => {
     inst.setLogLevel(level);
   });
 }
 
+// Alias for compatibility
+export const setLogLevelInternal = setLogLevel;
+
 /**
- * @type {setUserLogHandler}
+ * Sets a custom user log handler for all Logger instances
  */
-export function setUserLogHandler(logCallback, options) {
+export function setUserLogHandler(logCallback: LogCallback | null, options?: LogOptions): void {
   for (const instance of instances) {
-    let customLogLevel = null;
-    if (options && options.level) {
+    let customLogLevel: LogLevel | null = null;
+    if (options?.level) {
       customLogLevel = levelStringToEnum[options.level];
     }
     if (logCallback === null) {
       instance.userLogHandler = null;
     } else {
-      instance.userLogHandler = (instance, level, ...args) => {
+      instance.userLogHandler = (_instance, level, ...args) => {
         const message = args
           .map(arg => {
             if (arg == null) {
@@ -227,12 +256,12 @@ export function setUserLogHandler(logCallback, options) {
           })
           .filter(arg => arg)
           .join(' ');
-        if (level >= (customLogLevel ?? instance.logLevel)) {
+        if (level >= (customLogLevel ?? _instance.logLevel)) {
           logCallback({
-            level: LogLevelReversed[level].toLowerCase(),
+            level: LogLevelReversed[level]!.toLowerCase() as LogLevelString,
             message,
             args,
-            type: instance.name,
+            type: _instance.name,
           });
         }
       };
diff --git a/packages/app/lib/internal/nativeModule.android.js b/packages/app/lib/internal/nativeModule.android.ts
similarity index 100%
rename from packages/app/lib/internal/nativeModule.android.js
rename to packages/app/lib/internal/nativeModule.android.ts
diff --git a/packages/app/lib/internal/nativeModule.ios.js b/packages/app/lib/internal/nativeModule.ios.ts
similarity index 100%
rename from packages/app/lib/internal/nativeModule.ios.js
rename to packages/app/lib/internal/nativeModule.ios.ts
diff --git a/packages/app/lib/internal/nativeModule.js b/packages/app/lib/internal/nativeModule.ts
similarity index 100%
rename from packages/app/lib/internal/nativeModule.js
rename to packages/app/lib/internal/nativeModule.ts
diff --git a/packages/app/lib/internal/nativeModuleAndroidIos.js b/packages/app/lib/internal/nativeModuleAndroidIos.js
deleted file mode 100644
index 8254e4a91a..0000000000
--- a/packages/app/lib/internal/nativeModuleAndroidIos.js
+++ /dev/null
@@ -1,46 +0,0 @@
-/* eslint-disable no-console */
-import { NativeModules } from 'react-native';
-import { TurboModuleRegistry } from 'react-native';
-
-/**
- * This is used by Android and iOS to get a native module.
- * We additionally add a Proxy to the module to intercept calls
- * and log them to the console for debugging purposes, if enabled.
- * @param moduleName
- */
-export function getReactNativeModule(moduleName) {
-  const nativeModule = NativeModules[moduleName] || TurboModuleRegistry.get(moduleName);
-  if (!globalThis.RNFBDebug) {
-    return nativeModule;
-  }
-  return new Proxy(nativeModule, {
-    ownKeys(target) {
-      return Object.keys(target);
-    },
-    get: (_, name) => {
-      if (typeof nativeModule[name] !== 'function') return nativeModule[name];
-      return (...args) => {
-        console.debug(`[RNFB->Native][🔵] ${moduleName}.${name} -> ${JSON.stringify(args)}`);
-        const result = nativeModule[name](...args);
-        if (result && result.then) {
-          return result.then(
-            res => {
-              console.debug(`[RNFB<-Native][🟢] ${moduleName}.${name} <- ${JSON.stringify(res)}`);
-              return res;
-            },
-            err => {
-              console.debug(`[RNFB<-Native][🔴] ${moduleName}.${name} <- ${JSON.stringify(err)}`);
-              throw err;
-            },
-          );
-        }
-        console.debug(`[RNFB<-Native][🟢] ${moduleName}.${name} <- ${JSON.stringify(result)}`);
-        return result;
-      };
-    },
-  });
-}
-
-export function setReactNativeModule() {
-  // No-op
-}
diff --git a/packages/app/lib/internal/nativeModuleAndroidIos.ts b/packages/app/lib/internal/nativeModuleAndroidIos.ts
new file mode 100644
index 0000000000..ad6c02fb82
--- /dev/null
+++ b/packages/app/lib/internal/nativeModuleAndroidIos.ts
@@ -0,0 +1,55 @@
+/* eslint-disable no-console */
+import { NativeModules } from 'react-native';
+
+/**
+ * This is used by Android and iOS to get a native module.
+ * We additionally add a Proxy to the module to intercept calls
+ * and log them to the console for debugging purposes, if enabled.
+ * @param moduleName
+ * @returns Raw native module from React Native (object with methods/properties or undefined)
+ */
+export function getReactNativeModule(moduleName: string): Record<string, unknown> | undefined {
+  const nativeModule = NativeModules[moduleName];
+  if (!globalThis.RNFBDebug) {
+    return nativeModule;
+  }
+  return new Proxy(nativeModule, {
+    ownKeys(target) {
+      return Object.keys(target);
+    },
+    get: (_, name) => {
+      const prop = nativeModule[name as string];
+      if (typeof prop !== 'function') return prop;
+      return (...args: unknown[]) => {
+        console.debug(
+          `[RNFB->Native][🔵] ${moduleName}.${String(name)} -> ${JSON.stringify(args)}`,
+        );
+        const result: unknown = (prop as (...args: unknown[]) => unknown)(...args);
+        if (result && typeof result === 'object' && 'then' in result) {
+          return (result as Promise<unknown>).then(
+            (res: unknown) => {
+              console.debug(
+                `[RNFB<-Native][🟢] ${moduleName}.${String(name)} <- ${JSON.stringify(res)}`,
+              );
+              return res;
+            },
+            (err: unknown) => {
+              console.debug(
+                `[RNFB<-Native][🔴] ${moduleName}.${String(name)} <- ${JSON.stringify(err)}`,
+              );
+              throw err;
+            },
+          );
+        }
+        console.debug(
+          `[RNFB<-Native][🟢] ${moduleName}.${String(name)} <- ${JSON.stringify(result)}`,
+        );
+        return result;
+      };
+    },
+  });
+}
+
+export function setReactNativeModule(): void {
+  // No-op
+}
diff --git a/packages/app/lib/internal/nativeModuleWeb.js b/packages/app/lib/internal/nativeModuleWeb.js
deleted file mode 100644
index e39f939575..0000000000
--- a/packages/app/lib/internal/nativeModuleWeb.js
+++ /dev/null
@@ -1,49 +0,0 @@
-/* eslint-disable no-console */
-
-import RNFBAppModule from './web/RNFBAppModule';
-
-const nativeModuleRegistry = {};
-
-export function getReactNativeModule(moduleName) {
-  const nativeModule = nativeModuleRegistry[moduleName];
-  // Throw an error if the module is not registered.
-  if (!nativeModule) {
-    throw new Error(`Native module ${moduleName} is not registered.`);
-  }
-  if (!globalThis.RNFBDebug) {
-    return nativeModule;
-  }
-  return new Proxy(nativeModule, {
-    ownKeys(target) {
-      // FIXME - test in new arch context - I don't think Object.keys works
-      return Object.keys(target);
-    },
-    get: (_, name) => {
-      if (typeof nativeModule[name] !== 'function') return nativeModule[name];
-      return (...args) => {
-        console.debug(`[RNFB->Native][🔵] ${moduleName}.${name} -> ${JSON.stringify(args)}`);
-        const result = nativeModule[name](...args);
-        if (result && result.then) {
-          return result.then(
-            res => {
-              console.debug(`[RNFB<-Native][🟢] ${moduleName}.${name} <- ${JSON.stringify(res)}`);
-              return res;
-            },
-            err => {
-              console.debug(`[RNFB<-Native][🔴] ${moduleName}.${name} <- ${JSON.stringify(err)}`);
-              throw err;
-            },
-          );
-        }
-        console.debug(`[RNFB<-Native][🟢] ${moduleName}.${name} <- ${JSON.stringify(result)}`);
-        return result;
-      };
-    },
-  });
-}
-
-export function setReactNativeModule(moduleName, nativeModule) {
-  nativeModuleRegistry[moduleName] = nativeModule;
-}
-
-setReactNativeModule('RNFBAppModule', RNFBAppModule);
diff --git a/packages/app/lib/internal/nativeModuleWeb.ts b/packages/app/lib/internal/nativeModuleWeb.ts
new file mode 100644
index 0000000000..cc4e7d02d7
--- /dev/null
+++ b/packages/app/lib/internal/nativeModuleWeb.ts
@@ -0,0 +1,60 @@
+/* eslint-disable no-console */
+import RNFBAppModule from './web/RNFBAppModule';
+
+const nativeModuleRegistry: Record<string, Record<string, unknown>> = {};
+
+export function getReactNativeModule(moduleName: string): Record<string, unknown> | undefined {
+  const nativeModule = nativeModuleRegistry[moduleName];
+  // Throw an error if the module is not registered.
+  if (!nativeModule) {
+    throw new Error(`Native module ${moduleName} is not registered.`);
+  }
+  if (!globalThis.RNFBDebug) {
+    return nativeModule;
+  }
+  return new Proxy(nativeModule, {
+    ownKeys(target) {
+      // FIXME - test in new arch context - I don't think Object.keys works
+      return Object.keys(target);
+    },
+    get: (_, name) => {
+      const prop = nativeModule[name as string];
+      if (typeof prop !== 'function') return prop;
+      return (...args: unknown[]) => {
+        console.debug(
+          `[RNFB->Native][🔵] ${moduleName}.${String(name)} -> ${JSON.stringify(args)}`,
+        );
+        const result: unknown = (prop as (...args: unknown[]) => unknown)(...args);
+        if (result && typeof result === 'object' && 'then' in result) {
+          return (result as Promise<unknown>).then(
+            (res: unknown) => {
+              console.debug(
+                `[RNFB<-Native][🟢] ${moduleName}.${String(name)} <- ${JSON.stringify(res)}`,
+              );
+              return res;
+            },
+            (err: unknown) => {
+              console.debug(
+                `[RNFB<-Native][🔴] ${moduleName}.${String(name)} <- ${JSON.stringify(err)}`,
+              );
+              throw err;
+            },
+          );
+        }
+        console.debug(
+          `[RNFB<-Native][🟢] ${moduleName}.${String(name)} <- ${JSON.stringify(result)}`,
+        );
+        return result;
+      };
+    },
+  });
+}
+
+export function setReactNativeModule(
+  moduleName: string,
+  nativeModule: Record<string, unknown>,
+): void {
+  nativeModuleRegistry[moduleName] = nativeModule;
+}
+
+setReactNativeModule('RNFBAppModule', RNFBAppModule);
diff --git a/packages/app/lib/internal/nullSerialization.js b/packages/app/lib/internal/nullSerialization.ts
similarity index 54%
rename from packages/app/lib/internal/nullSerialization.js
rename to packages/app/lib/internal/nullSerialization.ts
index 6edc36d6b9..f918498952 100644
--- a/packages/app/lib/internal/nullSerialization.js
+++ b/packages/app/lib/internal/nullSerialization.ts
@@ -17,6 +17,27 @@
 
 const NULL_SENTINEL = { __rnfbNull: true };
 
+type Encodable = string | number | boolean | null | EncodableObject | EncodableArray;
+type EncodableObject = { [key: string]: Encodable };
+type EncodableArray = Encodable[];
+
+type ArrayFrame = {
+  type: 'array';
+  original: unknown[];
+  encoded: unknown[];
+  index: number;
+};
+
+type ObjectFrame = {
+  type: 'object';
+  original: Record<string, unknown>;
+  encoded: Record<string, unknown>;
+  keys: string[];
+  index: number;
+};
+
+type StackFrame = ArrayFrame | ObjectFrame;
+
 /**
  * Replaces null values in object properties with sentinel objects for iOS TurboModule compatibility.
  * Uses iterative stack-based traversal to avoid stack overflow on deeply nested structures.
@@ -28,10 +49,10 @@ const NULL_SENTINEL = { __rnfbNull: true };
  * Note: Null values in arrays are preserved by iOS TurboModules, so we don't
  * encode them (but we still process nested objects within arrays).
  *
- * @param {any} data - The data to encode
- * @returns {any} - The encoded data with null object properties replaced by sentinels
+ * @param data - The data to encode
+ * @returns The encoded data with null object properties replaced by sentinels
  */
-export function encodeNullValues(data) {
+export function encodeNullValues(data: unknown): unknown {
   if (data === null) {
     // only null values within objects are encoded
     return null;
@@ -41,15 +62,20 @@ export function encodeNullValues(data) {
   }
 
   // Helper to process a child element and add it to the encoded container
-  function processChild(child, encoded, keyOrIndex, isArray, stack) {
+  function processArrayChild(
+    child: unknown,
+    encoded: unknown[],
+    index: number,
+    stack: StackFrame[],
+  ): void {
     if (child === null) {
-      // Arrays preserve nulls as null, objects convert to sentinel
-      encoded[keyOrIndex] = isArray ? null : NULL_SENTINEL;
+      // Arrays preserve nulls as null
+      encoded[index] = null;
     } else if (typeof child !== 'object') {
-      encoded[keyOrIndex] = child;
+      encoded[index] = child;
     } else if (Array.isArray(child)) {
-      const childEncoded = new Array(child.length);
-      encoded[keyOrIndex] = childEncoded;
+      const childEncoded: unknown[] = new Array(child.length);
+      encoded[index] = childEncoded;
       stack.push({
         type: 'array',
         original: child,
@@ -57,12 +83,45 @@ export function encodeNullValues(data) {
         index: 0,
       });
     } else {
-      const childEncoded = {};
-      encoded[keyOrIndex] = childEncoded;
+      const childEncoded: Record<string, unknown> = {};
+      encoded[index] = childEncoded;
       stack.push({
         type: 'object',
+        original: child as Record<string, unknown>,
+        encoded: childEncoded,
+        keys: Object.keys(child),
+        index: 0,
+      });
+    }
+  }
+
+  function processObjectChild(
+    child: unknown,
+    encoded: Record<string, unknown>,
+    key: string,
+    stack: StackFrame[],
+  ): void {
+    if (child === null) {
+      // Objects convert null to sentinel
+      encoded[key] = NULL_SENTINEL;
+    } else if (typeof child !== 'object') {
+      encoded[key] = child;
+    } else if (Array.isArray(child)) {
+      const childEncoded: unknown[] = new Array(child.length);
+      encoded[key] = childEncoded;
+      stack.push({
+        type: 'array',
         original: child,
         encoded: childEncoded,
+        index: 0,
+      });
+    } else {
+      const childEncoded: Record<string, unknown> = {};
+      encoded[key] = childEncoded;
+      stack.push({
+        type: 'object',
+        original: child as Record<string, unknown>,
+        encoded: childEncoded,
         keys: Object.keys(child),
         index: 0,
       });
@@ -70,8 +129,8 @@ export function encodeNullValues(data) {
   }
 
   // Prepare root encoded container
-  let rootEncoded;
-  const stack = [];
+  let rootEncoded: unknown[] | Record<string, unknown>;
+  const stack: StackFrame[] = [];
 
   if (Array.isArray(data)) {
     rootEncoded = new Array(data.length);
@@ -85,7 +144,7 @@ export function encodeNullValues(data) {
     rootEncoded = {};
     stack.push({
       type: 'object',
-      original: data,
+      original: data as Record<string, unknown>,
       encoded: rootEncoded,
       keys: Object.keys(data),
       index: 0,
@@ -93,7 +152,7 @@ export function encodeNullValues(data) {
   }
 
   while (stack.length > 0) {
-    const frame = stack[stack.length - 1];
+    const frame = stack[stack.length - 1]!; // Non-null assertion safe due to while condition
 
     if (frame.type === 'array') {
       const { original, encoded } = frame;
@@ -106,7 +165,7 @@ export function encodeNullValues(data) {
 
       const i = frame.index++;
       const item = original[i];
-      processChild(item, encoded, i, true, stack);
+      processArrayChild(item, encoded, i, stack);
     } else {
       // frame.type === 'object'
       const { original, encoded, keys } = frame;
@@ -117,9 +176,9 @@ export function encodeNullValues(data) {
         continue;
       }
 
-      const key = keys[frame.index++];
+      const key = keys[frame.index++]!; // Non-null assertion safe due to length check above
       const value = original[key];
-      processChild(value, encoded, key, false, stack);
+      processObjectChild(value, encoded, key, stack);
     }
   }
 
diff --git a/packages/app/lib/internal/registry/app.js b/packages/app/lib/internal/registry/app.ts
similarity index 74%
rename from packages/app/lib/internal/registry/app.js
rename to packages/app/lib/internal/registry/app.ts
index fda5741665..98c1916347 100644
--- a/packages/app/lib/internal/registry/app.js
+++ b/packages/app/lib/internal/registry/app.ts
@@ -24,23 +24,28 @@ import {
   isFunction,
   isString,
   isUndefined,
-} from '@react-native-firebase/app/lib/common';
+} from '../../common';
 import FirebaseApp from '../../FirebaseApp';
 import { DEFAULT_APP_NAME } from '../constants';
 import { setReactNativeAsyncStorageInternal } from '../asyncStorage';
 import { getAppModule } from './nativeModule';
 import { setLogLevelInternal } from '../logger';
+import type { ReactNativeFirebase } from '../../types/app';
 
-const APP_REGISTRY = {};
-let onAppCreateFn = null;
-let onAppDestroyFn = null;
+type FirebaseAppConfig = ReactNativeFirebase.FirebaseAppConfig;
+type FirebaseAppOptions = ReactNativeFirebase.FirebaseAppOptions;
+type ReactNativeAsyncStorage = ReactNativeFirebase.ReactNativeAsyncStorage;
+
+const APP_REGISTRY: Record<string, FirebaseApp> = {};
+let onAppCreateFn: ((app: FirebaseApp) => void) | null = null;
+let onAppDestroyFn: ((app: FirebaseApp) => void) | null = null;
 let initializedNativeApps = false;
 
 /**
  * This was needed to avoid metro require cycles...
  * @param fn
  */
-export function setOnAppCreate(fn) {
+export function setOnAppCreate(fn: (app: FirebaseApp) => void): void {
   onAppCreateFn = fn;
 }
 
@@ -48,7 +53,7 @@ export function setOnAppCreate(fn) {
  * This was needed to avoid metro require cycles...
  * @param fn
  */
-export function setOnAppDestroy(fn) {
+export function setOnAppDestroy(fn: (app: FirebaseApp) => void): void {
   onAppDestroyFn = fn;
 }
 
@@ -56,21 +61,23 @@ export function setOnAppDestroy(fn) {
  * Initializes all apps that were created natively (android/ios),
  * e.g. the Default firebase app from plist/json google services file.
  */
-export function initializeNativeApps() {
+export function initializeNativeApps(): void {
   const nativeModule = getAppModule();
   const { NATIVE_FIREBASE_APPS } = nativeModule;
 
   if (NATIVE_FIREBASE_APPS && NATIVE_FIREBASE_APPS.length) {
     for (let i = 0; i < NATIVE_FIREBASE_APPS.length; i++) {
-      const { appConfig, options } = NATIVE_FIREBASE_APPS[i];
-      const { name } = appConfig;
+      const nativeApp = NATIVE_FIREBASE_APPS[i];
+      if (!nativeApp) continue;
+      const { appConfig, options } = nativeApp;
+      const name = appConfig.name as string;
       APP_REGISTRY[name] = new FirebaseApp(
-        options,
-        appConfig,
+        options as FirebaseAppOptions,
+        appConfig as FirebaseAppConfig,
         true,
         deleteApp.bind(null, name, true),
       );
-      onAppCreateFn(APP_REGISTRY[name]);
+      onAppCreateFn?.(APP_REGISTRY[name]);
     }
   }
 
@@ -85,7 +92,7 @@ export function initializeNativeApps() {
  *
  * @param name
  */
-export function getApp(name = DEFAULT_APP_NAME) {
+export function getApp(name: string = DEFAULT_APP_NAME): ReactNativeFirebase.FirebaseApp {
   warnIfNotModularCall(arguments, 'getApp()');
   if (!initializedNativeApps) {
     initializeNativeApps();
@@ -96,18 +103,18 @@ export function getApp(name = DEFAULT_APP_NAME) {
     throw new Error(`No Firebase App '${name}' has been created - call firebase.initializeApp()`);
   }
 
-  return app;
+  return app as unknown as ReactNativeFirebase.FirebaseApp;
 }
 
 /**
  * Gets all app instances, used for `firebase.apps`
  */
-export function getApps() {
+export function getApps(): ReactNativeFirebase.FirebaseApp[] {
   warnIfNotModularCall(arguments, 'getApps()');
   if (!initializedNativeApps) {
     initializeNativeApps();
   }
-  return Object.values(APP_REGISTRY);
+  return Object.values(APP_REGISTRY) as unknown as ReactNativeFirebase.FirebaseApp[];
 }
 
 /**
@@ -115,13 +122,16 @@ export function getApps() {
  * @param options
  * @param configOrName
  */
-export function initializeApp(options = {}, configOrName) {
+export function initializeApp(
+  options: Partial<FirebaseAppOptions> = {},
+  configOrName?: string | FirebaseAppConfig,
+): Promise<ReactNativeFirebase.FirebaseApp> {
   warnIfNotModularCall(arguments, 'initializeApp()');
-  let appConfig = configOrName;
+  let appConfig: FirebaseAppConfig = configOrName as FirebaseAppConfig;
 
   if (!isObject(configOrName) || isNull(configOrName)) {
     appConfig = {
-      name: configOrName,
+      name: configOrName as string,
       automaticResourceManagement: false,
       automaticDataCollectionEnabled: true,
     };
@@ -179,20 +189,25 @@ export function initializeApp(options = {}, configOrName) {
     );
   }
 
-  const app = new FirebaseApp(options, appConfig, false, deleteApp.bind(null, name, true));
+  const app = new FirebaseApp(
+    options as FirebaseAppOptions,
+    appConfig,
+    false,
+    deleteApp.bind(null, name, true),
+  );
 
   // Note these initialization actions with side effects are performed prior to knowledge of
   // successful initialization in the native code. Native code *may* throw an error.
   APP_REGISTRY[name] = app;
-  onAppCreateFn(APP_REGISTRY[name]);
+  onAppCreateFn?.(APP_REGISTRY[name]);
 
   return getAppModule()
-    .initializeApp(options, appConfig)
+    .initializeApp(options as FirebaseAppOptions, appConfig)
     .then(() => {
       app._initialized = true;
-      return app;
+      return app as unknown as ReactNativeFirebase.FirebaseApp;
     })
-    .catch(e => {
+    .catch((e: any) => {
       // we need to clean the app entry from registry as the app does not actually exist
       // There are still possible side effects from `onAppCreateFn` to consider but as existing
       // code may rely on that function running prior to native create, re-ordering it is a semantic change
@@ -204,7 +219,7 @@ export function initializeApp(options = {}, configOrName) {
     });
 }
 
-export function setLogLevel(logLevel) {
+export function setLogLevel(logLevel: ReactNativeFirebase.LogLevelString): void {
   warnIfNotModularCall(arguments, 'setLogLevel()');
   if (!['error', 'warn', 'info', 'debug', 'verbose'].includes(logLevel)) {
     throw new Error('LogLevel must be one of "error", "warn", "info", "debug", "verbose"');
@@ -217,7 +232,7 @@ export function setLogLevel(logLevel) {
   }
 }
 
-export function setReactNativeAsyncStorage(asyncStorage) {
+export function setReactNativeAsyncStorage(asyncStorage: ReactNativeAsyncStorage): void {
   warnIfNotModularCall(arguments, 'setReactNativeAsyncStorage()');
 
   if (!isObject(asyncStorage)) {
@@ -236,13 +251,13 @@ export function setReactNativeAsyncStorage(asyncStorage) {
     throw new Error("setReactNativeAsyncStorage(*) 'asyncStorage.removeItem' must be a function.");
   }
 
-  setReactNativeAsyncStorageInternal(asyncStorage);
+  setReactNativeAsyncStorageInternal(asyncStorage as any);
 }
 
 /**
  *
  */
-export function deleteApp(name, nativeInitialized) {
+export function deleteApp(name: string, nativeInitialized: boolean): Promise<void> {
   if (name === DEFAULT_APP_NAME && nativeInitialized) {
     return Promise.reject(new Error('Unable to delete the default native firebase app instance.'));
   }
@@ -256,8 +271,8 @@ export function deleteApp(name, nativeInitialized) {
   const nativeModule = getAppModule();
 
   return nativeModule.deleteApp(name).then(() => {
-    app._deleted = true;
-    onAppDestroyFn(app);
+    (app as any)._deleted = true;
+    onAppDestroyFn?.(app);
     delete APP_REGISTRY[name];
   });
 }
diff --git a/packages/app/lib/internal/registry/namespace.js b/packages/app/lib/internal/registry/namespace.ts
similarity index 57%
rename from packages/app/lib/internal/registry/namespace.js
rename to packages/app/lib/internal/registry/namespace.ts
index 76e3078666..1c391ee2fb 100644
--- a/packages/app/lib/internal/registry/namespace.js
+++ b/packages/app/lib/internal/registry/namespace.ts
@@ -17,9 +17,10 @@
 
 import { isString, createDeprecationProxy } from '../../common';
 import FirebaseApp from '../../FirebaseApp';
-import SDK_VERSION from '../../version';
-import { DEFAULT_APP_NAME, KNOWN_NAMESPACES } from '../constants';
+import { version as SDK_VERSION } from '../../version';
+import { DEFAULT_APP_NAME, KNOWN_NAMESPACES, type KnownNamespace } from '../constants';
 import FirebaseModule from '../FirebaseModule';
+import type { ModuleGetter, FirebaseRoot, NamespaceConfig } from '../../types/internal';
 import {
   getApp,
   getApps,
@@ -31,12 +32,12 @@ import {
 } from './app';
 
 // firebase.X
-let FIREBASE_ROOT = null;
+let FIREBASE_ROOT: FirebaseRoot | null = null;
 
-const NAMESPACE_REGISTRY = {};
-const APP_MODULE_INSTANCE = {};
-const MODULE_GETTER_FOR_APP = {};
-const MODULE_GETTER_FOR_ROOT = {};
+const NAMESPACE_REGISTRY: Record<string, NamespaceConfig | undefined> = {};
+const APP_MODULE_INSTANCE: Record<string, Record<string, FirebaseModule<any>>> = {};
+const MODULE_GETTER_FOR_APP: Record<string, Record<string, ModuleGetter>> = {};
+const MODULE_GETTER_FOR_ROOT: Record<string, ModuleGetter> = {};
 
 /**
  * Attaches module namespace getters on every newly created app.
@@ -46,10 +47,12 @@ const MODULE_GETTER_FOR_ROOT = {};
 setOnAppCreate(app => {
   for (let i = 0; i < KNOWN_NAMESPACES.length; i++) {
     const moduleNamespace = KNOWN_NAMESPACES[i];
-    Object.defineProperty(app, moduleNamespace, {
-      enumerable: false,
-      get: firebaseAppModuleProxy.bind(null, app, moduleNamespace),
-    });
+    if (moduleNamespace) {
+      Object.defineProperty(app, moduleNamespace, {
+        enumerable: false,
+        get: firebaseAppModuleProxy.bind(null, app, moduleNamespace),
+      });
+    }
   }
 });
 
@@ -70,17 +73,20 @@ setOnAppDestroy(app => {
  * @param moduleNamespace
  * @returns {*}
  */
-function getOrCreateModuleForApp(app, moduleNamespace) {
-  if (MODULE_GETTER_FOR_APP[app.name] && MODULE_GETTER_FOR_APP[app.name][moduleNamespace]) {
-    return MODULE_GETTER_FOR_APP[app.name][moduleNamespace];
+function getOrCreateModuleForApp(app: FirebaseApp, moduleNamespace: KnownNamespace): ModuleGetter {
+  if (MODULE_GETTER_FOR_APP[app.name] && MODULE_GETTER_FOR_APP[app.name]?.[moduleNamespace]) {
+    return MODULE_GETTER_FOR_APP[app.name]![moduleNamespace]!;
   }
 
   if (!MODULE_GETTER_FOR_APP[app.name]) {
     MODULE_GETTER_FOR_APP[app.name] = {};
   }
 
-  const { hasCustomUrlOrRegionSupport, hasMultiAppSupport, ModuleClass } =
-    NAMESPACE_REGISTRY[moduleNamespace];
+  const config = NAMESPACE_REGISTRY[moduleNamespace];
+  if (!config) {
+    throw new Error(`Module namespace '${moduleNamespace}' is not registered.`);
+  }
+  const { hasCustomUrlOrRegionSupport, hasMultiAppSupport, ModuleClass } = config;
 
   // modules such as analytics only run on the default app
   if (!hasMultiAppSupport && app.name !== DEFAULT_APP_NAME) {
@@ -94,7 +100,7 @@ function getOrCreateModuleForApp(app, moduleNamespace) {
   }
 
   // e.g. firebase.storage(customUrlOrRegion), firebase.functions(customUrlOrRegion), firebase.firestore(databaseId), firebase.database(url)
-  function firebaseModuleWithArgs(customUrlOrRegionOrDatabaseId) {
+  function firebaseModuleWithArgs(customUrlOrRegionOrDatabaseId?: string): FirebaseModule<any> {
     if (customUrlOrRegionOrDatabaseId !== undefined) {
       if (!hasCustomUrlOrRegionSupport) {
         // TODO throw Module does not support arguments error
@@ -113,19 +119,24 @@ function getOrCreateModuleForApp(app, moduleNamespace) {
       APP_MODULE_INSTANCE[app.name] = {};
     }
 
-    if (!APP_MODULE_INSTANCE[app.name][key]) {
+    if (!APP_MODULE_INSTANCE[app.name]?.[key]) {
+      const moduleConfig = NAMESPACE_REGISTRY[moduleNamespace];
+      if (!moduleConfig) {
+        throw new Error(`Module namespace '${moduleNamespace}' is not registered.`);
+      }
       const module = createDeprecationProxy(
-        new ModuleClass(app, NAMESPACE_REGISTRY[moduleNamespace], customUrlOrRegionOrDatabaseId),
-      );
+        new ModuleClass(app, moduleConfig, customUrlOrRegionOrDatabaseId),
+      ) as unknown as FirebaseModule<any>;
 
-      APP_MODULE_INSTANCE[app.name][key] = module;
+      APP_MODULE_INSTANCE[app.name]![key] = module;
     }
 
-    return APP_MODULE_INSTANCE[app.name][key];
+    return APP_MODULE_INSTANCE[app.name]![key]!;
   }
 
-  MODULE_GETTER_FOR_APP[app.name][moduleNamespace] = firebaseModuleWithArgs;
-  return MODULE_GETTER_FOR_APP[app.name][moduleNamespace];
+  MODULE_GETTER_FOR_APP[app.name]![moduleNamespace] =
+    firebaseModuleWithArgs as unknown as ModuleGetter;
+  return MODULE_GETTER_FOR_APP[app.name]![moduleNamespace]!;
 }
 
 /**
@@ -133,18 +144,29 @@ function getOrCreateModuleForApp(app, moduleNamespace) {
  * @param moduleNamespace
  * @returns {*}
  */
-function getOrCreateModuleForRoot(moduleNamespace) {
+function getOrCreateModuleForRoot(moduleNamespace: KnownNamespace): ModuleGetter {
   if (MODULE_GETTER_FOR_ROOT[moduleNamespace]) {
     return MODULE_GETTER_FOR_ROOT[moduleNamespace];
   }
 
-  const { statics, hasMultiAppSupport, ModuleClass } = NAMESPACE_REGISTRY[moduleNamespace];
+  const config = NAMESPACE_REGISTRY[moduleNamespace];
+  if (!config) {
+    throw new Error(`Module namespace '${moduleNamespace}' is not registered.`);
+  }
+  const { statics, hasMultiAppSupport, ModuleClass } = config;
 
   // e.g. firebase.storage(app)
-  function firebaseModuleWithApp(app) {
+  function firebaseModuleWithApp(app?: FirebaseApp): FirebaseModule<any> {
     const _app = app || getApp();
 
-    if (!(_app instanceof FirebaseApp)) {
+    // Duck-type check for FirebaseApp (checking for required properties)
+    if (
+      !_app ||
+      typeof _app !== 'object' ||
+      !('name' in _app) ||
+      !('options' in _app) ||
+      typeof _app.name !== 'string'
+    ) {
       throw new Error(
         [
           `"firebase.${moduleNamespace}(app)" arg expects a FirebaseApp instance or undefined.`,
@@ -169,22 +191,28 @@ function getOrCreateModuleForRoot(moduleNamespace) {
       APP_MODULE_INSTANCE[_app.name] = {};
     }
 
-    if (!APP_MODULE_INSTANCE[_app.name][moduleNamespace]) {
+    if (!APP_MODULE_INSTANCE[_app.name]?.[moduleNamespace]) {
+      const moduleConfig = NAMESPACE_REGISTRY[moduleNamespace];
+      if (!moduleConfig) {
+        throw new Error(`Module namespace '${moduleNamespace}' is not registered.`);
+      }
       const module = createDeprecationProxy(
-        new ModuleClass(_app, NAMESPACE_REGISTRY[moduleNamespace]),
-      );
-      APP_MODULE_INSTANCE[_app.name][moduleNamespace] = module;
+        new ModuleClass(_app, moduleConfig),
+      ) as unknown as FirebaseModule<any>;
+      APP_MODULE_INSTANCE[_app.name]![moduleNamespace] = module;
     }
 
-    return APP_MODULE_INSTANCE[_app.name][moduleNamespace];
+    return APP_MODULE_INSTANCE[_app.name]![moduleNamespace]!;
   }
 
   Object.assign(firebaseModuleWithApp, statics || {});
   // Object.freeze(firebaseModuleWithApp);
   // Wrap around statics, e.g. firebase.firestore.FieldValue, removed freeze as it stops proxy working. it is deprecated anyway
-  MODULE_GETTER_FOR_ROOT[moduleNamespace] = createDeprecationProxy(firebaseModuleWithApp);
+  MODULE_GETTER_FOR_ROOT[moduleNamespace] = createDeprecationProxy(
+    firebaseModuleWithApp,
+  ) as unknown as ModuleGetter;
 
-  return MODULE_GETTER_FOR_ROOT[moduleNamespace];
+  return MODULE_GETTER_FOR_ROOT[moduleNamespace]!;
 }
 
 /**
@@ -193,12 +221,15 @@ function getOrCreateModuleForRoot(moduleNamespace) {
  * @param moduleNamespace
  * @returns {*}
  */
-function firebaseRootModuleProxy(_firebaseNamespace, moduleNamespace) {
+function firebaseRootModuleProxy(
+  _firebaseNamespace: FirebaseRoot,
+  moduleNamespace: string,
+): ModuleGetter {
   if (NAMESPACE_REGISTRY[moduleNamespace]) {
-    return getOrCreateModuleForRoot(moduleNamespace);
+    return getOrCreateModuleForRoot(moduleNamespace as KnownNamespace);
   }
 
-  moduleWithDashes = moduleNamespace
+  const moduleWithDashes = moduleNamespace
     .split(/(?=[A-Z])/)
     .join('-')
     .toLowerCase();
@@ -218,13 +249,14 @@ function firebaseRootModuleProxy(_firebaseNamespace, moduleNamespace) {
  * @param moduleNamespace
  * @returns {*}
  */
-export function firebaseAppModuleProxy(app, moduleNamespace) {
+export function firebaseAppModuleProxy(app: FirebaseApp, moduleNamespace: string): ModuleGetter {
   if (NAMESPACE_REGISTRY[moduleNamespace]) {
-    app._checkDestroyed();
-    return getOrCreateModuleForApp(app, moduleNamespace);
+    // Call private _checkDestroyed method
+    (app as unknown as { _checkDestroyed: () => void })._checkDestroyed();
+    return getOrCreateModuleForApp(app, moduleNamespace as KnownNamespace);
   }
 
-  moduleWithDashes = moduleNamespace
+  const moduleWithDashes = moduleNamespace
     .split(/(?=[A-Z])/)
     .join('-')
     .toLowerCase();
@@ -242,8 +274,9 @@ export function firebaseAppModuleProxy(app, moduleNamespace) {
  *
  * @returns {*}
  */
-export function createFirebaseRoot() {
-  FIREBASE_ROOT = {
+export function createFirebaseRoot(): FirebaseRoot {
+  // Create partial root object - module namespaces like 'utils' are added dynamically below
+  const root = {
     initializeApp,
     setReactNativeAsyncStorage,
     get app() {
@@ -254,24 +287,27 @@ export function createFirebaseRoot() {
     },
     SDK_VERSION,
     setLogLevel,
-  };
+  } as FirebaseRoot;
 
   for (let i = 0; i < KNOWN_NAMESPACES.length; i++) {
     const namespace = KNOWN_NAMESPACES[i];
-    Object.defineProperty(FIREBASE_ROOT, namespace, {
-      enumerable: false,
-      get: firebaseRootModuleProxy.bind(null, FIREBASE_ROOT, namespace),
-    });
+    if (namespace) {
+      Object.defineProperty(root, namespace, {
+        enumerable: false,
+        get: firebaseRootModuleProxy.bind(null, root, namespace),
+      });
+    }
   }
 
-  return FIREBASE_ROOT;
+  FIREBASE_ROOT = root;
+  return root;
 }
 
 /**
  *
  * @returns {*}
  */
-export function getFirebaseRoot() {
+export function getFirebaseRoot(): FirebaseRoot {
   if (FIREBASE_ROOT) {
     return FIREBASE_ROOT;
   }
@@ -283,17 +319,20 @@ export function getFirebaseRoot() {
  * @param options
  * @returns {*}
  */
-export function createModuleNamespace(options = {}) {
+export function createModuleNamespace(options: NamespaceConfig): ModuleGetter {
   const { namespace, ModuleClass } = options;
 
   if (!NAMESPACE_REGISTRY[namespace]) {
     // validation only for internal / module dev usage
-    if (FirebaseModule.__extended__ !== ModuleClass.__extended__) {
+    const firebaseModuleExtended = (FirebaseModule as unknown as { __extended__: object })
+      .__extended__;
+    const moduleClassExtended = (ModuleClass as unknown as { __extended__: object }).__extended__;
+    if (firebaseModuleExtended !== moduleClassExtended) {
       throw new Error('INTERNAL ERROR: ModuleClass must be an instance of FirebaseModule.');
     }
 
     NAMESPACE_REGISTRY[namespace] = Object.assign({}, options);
   }
 
-  return getFirebaseRoot()[namespace];
+  return getFirebaseRoot()[namespace] as ModuleGetter;
 }
diff --git a/packages/app/lib/internal/registry/nativeModule.js b/packages/app/lib/internal/registry/nativeModule.ts
similarity index 68%
rename from packages/app/lib/internal/registry/nativeModule.js
rename to packages/app/lib/internal/registry/nativeModule.ts
index 43611e46d0..559997b248 100644
--- a/packages/app/lib/internal/registry/nativeModule.js
+++ b/packages/app/lib/internal/registry/nativeModule.ts
@@ -16,16 +16,25 @@
  */
 import { APP_NATIVE_MODULE } from '../constants';
 import NativeFirebaseError from '../NativeFirebaseError';
+import type { NativeError } from '../../types/internal';
 import RNFBNativeEventEmitter from '../RNFBNativeEventEmitter';
 import SharedEventEmitter from '../SharedEventEmitter';
 import { getReactNativeModule } from '../nativeModule';
 import { isAndroid, isIOS } from '../../common';
+import FirebaseModule from '../FirebaseModule';
+import type { WrappedNativeModule, RNFBAppModuleInterface } from '../NativeModules';
 import { encodeNullValues } from '../nullSerialization';
 
-const NATIVE_MODULE_REGISTRY = {};
-const NATIVE_MODULE_EVENT_SUBSCRIPTIONS = {};
+interface NativeEvent {
+  appName?: string;
+  databaseId?: string;
+  [key: string]: unknown;
+}
+
+const NATIVE_MODULE_REGISTRY: Record<string, WrappedNativeModule> = {};
+const NATIVE_MODULE_EVENT_SUBSCRIPTIONS: Record<string, boolean> = {};
 
-function nativeModuleKey(module) {
+function nativeModuleKey(module: FirebaseModule): string {
   return `${module._customUrlOrRegion || ''}:${module.app.name}:${module._config.namespace}`;
 }
 
@@ -38,8 +47,13 @@ function nativeModuleKey(module) {
  * @param argToPrepend
  * @returns {Function}
  */
-function nativeModuleMethodWrapped(namespace, method, argToPrepend, isTurboModule) {
-  return (...args) => {
+function nativeModuleMethodWrapped(
+  namespace: string,
+  method: (...args: unknown[]) => unknown,
+  argToPrepend: unknown[],
+  isTurboModule: boolean,
+): (...args: unknown[]) => unknown {
+  return (...args: unknown[]) => {
     // For iOS TurboModules, encode null values in arguments to work around
     // the limitation where null values in object properties get stripped during serialization
     // See: https://github.com/facebook/react-native/issues/52802
@@ -47,10 +61,10 @@ function nativeModuleMethodWrapped(namespace, method, argToPrepend, isTurboModul
     const allArgs = [...argToPrepend, ...processedArgs];
     const possiblePromise = method(...allArgs);
 
-    if (possiblePromise && possiblePromise.then) {
+    if (possiblePromise && typeof possiblePromise === 'object' && 'then' in possiblePromise) {
       const jsStack = new Error().stack;
-      return possiblePromise.catch(nativeError =>
-        Promise.reject(new NativeFirebaseError(nativeError, jsStack, namespace)),
+      return (possiblePromise as Promise<unknown>).catch((nativeError: NativeError) =>
+        Promise.reject(new NativeFirebaseError(nativeError, jsStack as string, namespace)),
       );
     }
 
@@ -62,29 +76,36 @@ function nativeModuleMethodWrapped(namespace, method, argToPrepend, isTurboModul
  * Prepends all arguments in prependArgs to all native method calls
  *
  * @param namespace
- * @param NativeModule
+ * @param NativeModule - Raw native module from React Native
  * @param argToPrepend
  */
-function nativeModuleWrapped(namespace, NativeModule, argToPrepend, isTurboModule) {
-  const native = {};
+function nativeModuleWrapped(
+  namespace: string,
+  NativeModule: Record<string, unknown> | undefined,
+  argToPrepend: unknown[],
+  isTurboModule: boolean,
+): WrappedNativeModule {
+  const native: Record<string, unknown> = {};
   if (!NativeModule) {
-    return NativeModule;
+    return NativeModule as unknown as WrappedNativeModule;
   }
 
-  let properties = Object.keys(Object.getPrototypeOf(NativeModule));
-  if (!properties.length) properties = Object.keys(NativeModule);
+  const nativeModuleObj = NativeModule;
+  let properties = Object.keys(Object.getPrototypeOf(nativeModuleObj));
+  if (!properties.length) properties = Object.keys(nativeModuleObj);
 
   for (let i = 0, len = properties.length; i < len; i++) {
     const property = properties[i];
-    if (typeof NativeModule[property] === 'function') {
+    if (!property) continue;
+    if (typeof nativeModuleObj[property] === 'function') {
       native[property] = nativeModuleMethodWrapped(
         namespace,
-        NativeModule[property],
+        nativeModuleObj[property] as (...args: unknown[]) => unknown,
         argToPrepend,
         isTurboModule,
       );
     } else {
-      native[property] = NativeModule[property];
+      native[property] = nativeModuleObj[property];
     }
   }
 
@@ -97,7 +118,7 @@ function nativeModuleWrapped(namespace, NativeModule, argToPrepend, isTurboModul
  * @param module
  * @returns {*}
  */
-function initialiseNativeModule(module) {
+function initialiseNativeModule(module: FirebaseModule): WrappedNativeModule {
   const config = module._config;
   const key = nativeModuleKey(module);
   const {
@@ -109,13 +130,16 @@ function initialiseNativeModule(module) {
     disablePrependCustomUrlOrRegion,
     turboModule,
   } = config;
+  const multiModuleRoot: WrappedNativeModule = {};
   const isTurboModule = !!turboModule;
-  const multiModuleRoot = {};
   const multiModule = Array.isArray(nativeModuleName);
   const nativeModuleNames = multiModule ? nativeModuleName : [nativeModuleName];
 
   for (let i = 0; i < nativeModuleNames.length; i++) {
-    const nativeModule = getReactNativeModule(nativeModuleNames[i]);
+    const moduleName = nativeModuleNames[i];
+    if (!moduleName) continue;
+
+    const nativeModule = getReactNativeModule(moduleName);
 
     // only error if there's a single native module
     // as multi modules can mean some are optional
@@ -124,17 +148,17 @@ function initialiseNativeModule(module) {
     }
 
     if (multiModule) {
-      multiModuleRoot[nativeModuleNames[i]] = !!nativeModule;
+      multiModuleRoot[moduleName] = !!nativeModule;
     }
 
-    const argToPrepend = [];
+    const argToPrepend: Array<string> = [];
 
     if (hasMultiAppSupport) {
       argToPrepend.push(module.app.name);
     }
 
     if (hasCustomUrlOrRegionSupport && !disablePrependCustomUrlOrRegion) {
-      argToPrepend.push(module._customUrlOrRegion);
+      argToPrepend.push(module._customUrlOrRegion as string);
     }
 
     Object.assign(
@@ -143,9 +167,12 @@ function initialiseNativeModule(module) {
     );
   }
 
-  if (nativeEvents && nativeEvents.length) {
+  if (nativeEvents && Array.isArray(nativeEvents) && nativeEvents.length) {
     for (let i = 0, len = nativeEvents.length; i < len; i++) {
-      subscribeToNativeModuleEvent(nativeEvents[i]);
+      const eventName = nativeEvents[i];
+      if (eventName) {
+        subscribeToNativeModuleEvent(eventName);
+      }
     }
   }
 
@@ -165,9 +192,10 @@ function initialiseNativeModule(module) {
  * @param eventName
  * @private
  */
-function subscribeToNativeModuleEvent(eventName) {
+function subscribeToNativeModuleEvent(eventName: string): void {
   if (!NATIVE_MODULE_EVENT_SUBSCRIPTIONS[eventName]) {
-    RNFBNativeEventEmitter.addListener(eventName, event => {
+    RNFBNativeEventEmitter.addListener(eventName, (...args: unknown[]) => {
+      const event = args[0] as NativeEvent;
       if (event.appName && event.databaseId) {
         // Firestore requires both appName and databaseId to prefix
         SharedEventEmitter.emit(`${event.appName}-${event.databaseId}-${eventName}`, event);
@@ -190,7 +218,7 @@ function subscribeToNativeModuleEvent(eventName) {
  * @param namespace
  * @returns {string}
  */
-function getMissingModuleHelpText(namespace) {
+function getMissingModuleHelpText(namespace: string): string {
   const snippet = `firebase.${namespace}()`;
 
   if (isIOS || isAndroid) {
@@ -215,7 +243,7 @@ function getMissingModuleHelpText(namespace) {
  * @param module
  * @returns {*}
  */
-export function getNativeModule(module) {
+export function getNativeModule(module: FirebaseModule): WrappedNativeModule {
   const key = nativeModuleKey(module);
 
   if (NATIVE_MODULE_REGISTRY[key]) {
@@ -230,9 +258,9 @@ export function getNativeModule(module) {
  *
  * @returns {*}
  */
-export function getAppModule() {
+export function getAppModule(): RNFBAppModuleInterface {
   if (NATIVE_MODULE_REGISTRY[APP_NATIVE_MODULE]) {
-    return NATIVE_MODULE_REGISTRY[APP_NATIVE_MODULE];
+    return NATIVE_MODULE_REGISTRY[APP_NATIVE_MODULE] as unknown as RNFBAppModuleInterface;
   }
 
   const namespace = 'app';
@@ -250,5 +278,5 @@ export function getAppModule() {
     false,
   );
 
-  return NATIVE_MODULE_REGISTRY[APP_NATIVE_MODULE];
+  return NATIVE_MODULE_REGISTRY[APP_NATIVE_MODULE] as unknown as RNFBAppModuleInterface;
 }
diff --git a/packages/app/lib/internal/web/RNFBAppModule.js b/packages/app/lib/internal/web/RNFBAppModule.js
deleted file mode 100644
index 35bb238e05..0000000000
--- a/packages/app/lib/internal/web/RNFBAppModule.js
+++ /dev/null
@@ -1,261 +0,0 @@
-import { initializeApp, setLogLevel, getApp, getApps, deleteApp } from './firebaseApp';
-
-import { DeviceEventEmitter } from 'react-native';
-
-// Variables for events tracking.
-let jsReady = false;
-let jsListenerCount = 0;
-let queuedEvents = [];
-let jsListeners = {};
-
-// For compatibility we have a fake preferences storage,
-// it does not persist across app restarts.
-let fakePreferencesStorage = {};
-
-function eventsGetListenersMap() {
-  return {
-    listeners: jsListenerCount,
-    queued: queuedEvents.length,
-    events: jsListeners,
-  };
-}
-
-function eventsSendEvent(eventName, eventBody) {
-  if (!jsReady || !jsListeners.hasOwnProperty(eventName)) {
-    const event = {
-      eventName,
-      eventBody,
-    };
-    queuedEvents.push(event);
-    return;
-  }
-  setImmediate(() => DeviceEventEmitter.emit('rnfb_' + eventName, eventBody));
-}
-
-function eventsSendQueuedEvents() {
-  if (queuedEvents.length === 0) {
-    return;
-  }
-  const events = Array.from(queuedEvents);
-  queuedEvents = [];
-  for (let i = 0; i < events.length; i++) {
-    const event = events[i];
-    eventsSendEvent(event.eventName, event.eventBody);
-  }
-}
-
-export default {
-  // Natively initialized apps, but in the case of web, we don't have any.
-  NATIVE_FIREBASE_APPS: [],
-  // The raw JSON string of the Firebase config, from the users firebase.json file.
-  // In the case of web, we can't support this.
-  FIREBASE_RAW_JSON: '{}',
-
-  /**
-   * Initializes a Firebase app.
-   *
-   * @param {object} options - The Firebase app options.
-   * @param {object} appConfig - The Firebase app config.
-   * @returns {object} - The Firebase app instance.
-   */
-  async initializeApp(options, appConfig) {
-    const name = appConfig.name;
-    const existingApp = getApps().find(app => app.name === name);
-    if (existingApp) {
-      return existingApp;
-    }
-    const newAppConfig = {
-      name,
-    };
-    if (
-      appConfig.automaticDataCollectionEnabled === true ||
-      appConfig.automaticDataCollectionEnabled === false
-    ) {
-      newAppConfig.automaticDataCollectionEnabled = appConfig.automaticDataCollectionEnabled;
-    }
-    const optionsCopy = Object.assign({}, options);
-
-    delete optionsCopy.clientId;
-    initializeApp(optionsCopy, newAppConfig);
-    return {
-      options,
-      appConfig,
-    };
-  },
-
-  /**
-   * Sets the log level for the Firebase app.
-   *
-   * @param {string} logLevel - The log level to set.
-   */
-  setLogLevel(logLevel) {
-    setLogLevel(logLevel);
-  },
-
-  /**
-   * Sets the automatic data collection for the Firebase app.
-   *
-   * @param {string} appName - The name of the Firebase app.
-   * @param {boolean} enabled - Whether to enable automatic data collection.
-   */
-  setAutomaticDataCollectionEnabled(appName, enabled) {
-    getApp(appName).automaticDataCollectionEnabled = enabled;
-  },
-
-  /**
-   * Deletes a Firebase app.
-   *
-   * @param {string} appName - The name of the Firebase app to delete.
-   */
-  async deleteApp(appName) {
-    if (getApp(appName)) {
-      deleteApp(appName);
-    }
-  },
-
-  /**
-   * Gets the meta data.
-   * Unsupported on web.
-   *
-   * @returns {object} - The meta data
-   */
-  metaGetAll() {
-    return {};
-  },
-
-  /**
-   * Gets the firebase.json data.
-   * Unsupported on web.
-   *
-   * @returns {object} - The JSON data for the firebase.json file.
-   */
-  jsonGetAll() {
-    return {};
-  },
-
-  /**
-   * Sets a boolean value for a preference.
-   * Unsupported on web.
-   *
-   * @param {string} key - The key of the preference.
-   * @param {boolean} value - The value to set.
-   */
-  async preferencesSetBool(key, value) {
-    fakePreferencesStorage[key] = value;
-  },
-
-  /**
-   * Sets a string value for a preference.
-   * Unsupported on web.
-   *
-   * @param {string} key - The key of the preference.
-   * @param {string} value - The value to set.
-   */
-  preferencesSetString(key, value) {
-    fakePreferencesStorage[key] = value;
-  },
-
-  /**
-   * Gets all preferences.
-   * Unsupported on web.
-   *
-   * @returns {object} - The preferences.
-   */
-  preferencesGetAll() {
-    return Object.assign({}, fakePreferencesStorage);
-  },
-
-  /**
-   * Clears all preferences.
-   * Unsupported on web.
-   */
-  preferencesClearAll() {
-    fakePreferencesStorage = {};
-  },
-
-  /**
-   * Adds a listener for an event.
-   * Unsupported on web.
-   *
-   * @param {string} eventName - The name of the event to listen for.
-   */
-  addListener() {
-    // Keep: Required for RN built in Event Emitter Calls.
-  },
-  /**
-   * Removes a listener for an event.
-   * Unsupported on web.
-   *
-   * @param {string} eventName - The name of the event to remove the listener for.
-   */
-  removeListeners() {
-    // Keep: Required for RN built in Event Emitter Calls.
-  },
-
-  /**
-   * Notifies the app that it is ready to receive events.
-   *
-   * @param {boolean} ready - Whether the app is ready to receive events.
-   * @returns {void}
-   */
-  eventsNotifyReady(ready) {
-    jsReady = ready;
-    if (jsReady) {
-      setImmediate(() => eventsSendQueuedEvents());
-    }
-  },
-
-  /**
-   * Gets all the listeners registered.
-   *
-   * @returns {object} - The listeners for the event.
-   */
-  eventsGetListeners() {
-    return eventsGetListenersMap();
-  },
-
-  /**
-   * Sends an event to the app for testing purposes.
-   *
-   * @param {string} eventName - The name of the event to send.
-   * @param {object} eventBody - The body of the event to send.
-   * @returns {void}
-   */
-  eventsPing(eventName, eventBody) {
-    eventsSendEvent(eventName, eventBody);
-  },
-
-  /**
-   * Adds a listener for an event.
-   *
-   * @param {string} eventName - The name of the event to listen for.
-   */
-  eventsAddListener(eventName) {
-    jsListenerCount++;
-    if (!jsListeners.hasOwnProperty(eventName)) {
-      jsListeners[eventName] = 1;
-    } else {
-      jsListeners[eventName]++;
-    }
-    setImmediate(() => eventsSendQueuedEvents());
-  },
-
-  /**
-   * Removes a single listener for an event or all listeners for an event.
-   *
-   * @param {string} eventName - The name of the event to remove the listener for.
-   * @param {boolean} all - Optional. Whether to remove all listeners for the event.
-   */
-  eventsRemoveListener(eventName, all) {
-    if (jsListeners.hasOwnProperty(eventName)) {
-      if (jsListeners[eventName] <= 1 || all) {
-        const count = jsListeners[eventName];
-        jsListenerCount -= count;
-        delete jsListeners[eventName];
-      } else {
-        jsListenerCount--;
-        jsListeners[eventName]--;
-      }
-    }
-  },
-};
diff --git a/packages/app/lib/internal/web/RNFBAppModule.ts b/packages/app/lib/internal/web/RNFBAppModule.ts
new file mode 100644
index 0000000000..257d28135a
--- /dev/null
+++ b/packages/app/lib/internal/web/RNFBAppModule.ts
@@ -0,0 +1,318 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import { initializeApp, setLogLevel, getApp, getApps, deleteApp } from './firebaseApp';
+import { DeviceEventEmitter } from 'react-native';
+import { type ReactNativeFirebase } from '../../index';
+
+// Types for internal state
+interface QueuedEvent {
+  eventName: string;
+  eventBody: any;
+}
+
+interface EventListeners {
+  [eventName: string]: number;
+}
+
+interface ListenersMap {
+  listeners: number;
+  queued: number;
+  events: EventListeners;
+}
+
+interface PreferencesStorage {
+  [key: string]: boolean | string;
+}
+
+interface InitializeAppResult {
+  options: ReactNativeFirebase.FirebaseAppOptions;
+  appConfig: ReactNativeFirebase.FirebaseAppConfig;
+}
+
+// Variables for events tracking.
+let jsReady = false;
+let jsListenerCount = 0;
+let queuedEvents: QueuedEvent[] = [];
+let jsListeners: EventListeners = {};
+
+// For compatibility we have a fake preferences storage,
+// it does not persist across app restarts.
+let fakePreferencesStorage: PreferencesStorage = {};
+
+function eventsGetListenersMap(): ListenersMap {
+  return {
+    listeners: jsListenerCount,
+    queued: queuedEvents.length,
+    events: jsListeners,
+  };
+}
+
+function eventsSendEvent(eventName: string, eventBody: any): void {
+  if (!jsReady || !jsListeners.hasOwnProperty(eventName)) {
+    const event: QueuedEvent = {
+      eventName,
+      eventBody,
+    };
+    queuedEvents.push(event);
+    return;
+  }
+  setImmediate(() => DeviceEventEmitter.emit('rnfb_' + eventName, eventBody));
+}
+
+function eventsSendQueuedEvents(): void {
+  if (queuedEvents.length === 0) {
+    return;
+  }
+  const events = Array.from(queuedEvents);
+  queuedEvents = [];
+  for (let i = 0; i < events.length; i++) {
+    const event = events[i];
+    if (event) {
+      eventsSendEvent(event.eventName, event.eventBody);
+    }
+  }
+}
+
+export default {
+  // Natively initialized apps, but in the case of web, we don't have any.
+  NATIVE_FIREBASE_APPS: [] as any[],
+  // The raw JSON string of the Firebase config, from the users firebase.json file.
+  // In the case of web, we can't support this.
+  FIREBASE_RAW_JSON: '{}',
+
+  /**
+   * Initializes a Firebase app.
+   *
+   * @param options - The Firebase app options.
+   * @param appConfig - The Firebase app config.
+   * @returns The Firebase app instance.
+   */
+  async initializeApp(
+    options: ReactNativeFirebase.FirebaseAppOptions,
+    appConfig: ReactNativeFirebase.FirebaseAppConfig,
+  ): Promise<InitializeAppResult> {
+    const name = appConfig.name;
+    const existingApp = getApps().find(app => app.name === name);
+    if (existingApp) {
+      return {
+        options,
+        appConfig,
+      };
+    }
+    const newAppConfig: any = {
+      name,
+    };
+    if (
+      appConfig.automaticDataCollectionEnabled === true ||
+      appConfig.automaticDataCollectionEnabled === false
+    ) {
+      newAppConfig.automaticDataCollectionEnabled = appConfig.automaticDataCollectionEnabled;
+    }
+    const optionsCopy = Object.assign({}, options);
+
+    delete (optionsCopy as any).clientId;
+    initializeApp(optionsCopy, newAppConfig);
+    return {
+      options,
+      appConfig,
+    };
+  },
+
+  /**
+   * Sets the log level for the Firebase app.
+   *
+   * @param logLevel - The log level to set.
+   */
+  setLogLevel(logLevel: ReactNativeFirebase.LogLevelString): void {
+    setLogLevel(logLevel as any);
+  },
+
+  /**
+   * Sets the automatic data collection for the Firebase app.
+   *
+   * @param appName - The name of the Firebase app.
+   * @param enabled - Whether to enable automatic data collection.
+   */
+  setAutomaticDataCollectionEnabled(appName: string, enabled: boolean): void {
+    (getApp(appName) as any).automaticDataCollectionEnabled = enabled;
+  },
+
+  /**
+   * Deletes a Firebase app.
+   *
+   * @param appName - The name of the Firebase app to delete.
+   */
+  async deleteApp(appName: string): Promise<void> {
+    if (getApp(appName)) {
+      await deleteApp(getApp(appName) as any);
+    }
+  },
+
+  /**
+   * Gets the meta data.
+   * Unsupported on web.
+   *
+   * @returns The meta data
+   */
+  metaGetAll(): Record<string, never> {
+    return {};
+  },
+
+  /**
+   * Gets the firebase.json data.
+   * Unsupported on web.
+   *
+   * @returns The JSON data for the firebase.json file.
+   */
+  jsonGetAll(): Record<string, never> {
+    return {};
+  },
+
+  /**
+   * Sets a boolean value for a preference.
+   * Unsupported on web.
+   *
+   * @param key - The key of the preference.
+   * @param value - The value to set.
+   */
+  async preferencesSetBool(key: string, value: boolean): Promise<void> {
+    fakePreferencesStorage[key] = value;
+  },
+
+  /**
+   * Sets a string value for a preference.
+   * Unsupported on web.
+   *
+   * @param key - The key of the preference.
+   * @param value - The value to set.
+   */
+  preferencesSetString(key: string, value: string): void {
+    fakePreferencesStorage[key] = value;
+  },
+
+  /**
+   * Gets all preferences.
+   * Unsupported on web.
+   *
+   * @returns The preferences.
+   */
+  preferencesGetAll(): PreferencesStorage {
+    return Object.assign({}, fakePreferencesStorage);
+  },
+
+  /**
+   * Clears all preferences.
+   * Unsupported on web.
+   */
+  preferencesClearAll(): void {
+    fakePreferencesStorage = {};
+  },
+
+  /**
+   * Adds a listener for an event.
+   * Unsupported on web.
+   *
+   * @param eventName - The name of the event to listen for.
+   */
+  addListener(): void {
+    // Keep: Required for RN built in Event Emitter Calls.
+  },
+  /**
+   * Removes a listener for an event.
+   * Unsupported on web.
+   *
+   * @param eventName - The name of the event to remove the listener for.
+   */
+  removeListeners(): void {
+    // Keep: Required for RN built in Event Emitter Calls.
+  },
+
+  /**
+   * Notifies the app that it is ready to receive events.
+   *
+   * @param ready - Whether the app is ready to receive events.
+   * @returns void
+   */
+  eventsNotifyReady(ready: boolean): void {
+    jsReady = ready;
+    if (jsReady) {
+      setImmediate(() => eventsSendQueuedEvents());
+    }
+  },
+
+  /**
+   * Gets all the listeners registered.
+   *
+   * @returns The listeners for the event.
+   */
+  eventsGetListeners(): ListenersMap {
+    return eventsGetListenersMap();
+  },
+
+  /**
+   * Sends an event to the app for testing purposes.
+   *
+   * @param eventName - The name of the event to send.
+   * @param eventBody - The body of the event to send.
+   * @returns void
+   */
+  eventsPing(eventName: string, eventBody: any): void {
+    eventsSendEvent(eventName, eventBody);
+  },
+
+  /**
+   * Adds a listener for an event.
+   *
+   * @param eventName - The name of the event to listen for.
+   */
+  eventsAddListener(eventName: string): void {
+    jsListenerCount++;
+    if (!jsListeners.hasOwnProperty(eventName)) {
+      jsListeners[eventName] = 1;
+    } else {
+      if (jsListeners[eventName] !== undefined) {
+        jsListeners[eventName]++;
+      }
+    }
+    setImmediate(() => eventsSendQueuedEvents());
+  },
+
+  /**
+   * Removes a single listener for an event or all listeners for an event.
+   *
+   * @param eventName - The name of the event to remove the listener for.
+   * @param all - Optional. Whether to remove all listeners for the event.
+   */
+  eventsRemoveListener(eventName: string, all?: boolean): void {
+    if (jsListeners.hasOwnProperty(eventName)) {
+      const count = jsListeners[eventName];
+      if (count !== undefined) {
+        if (count <= 1 || all) {
+          jsListenerCount -= count;
+          delete jsListeners[eventName];
+        } else {
+          jsListenerCount--;
+          const currentCount = jsListeners[eventName];
+          if (currentCount !== undefined) {
+            jsListeners[eventName] = currentCount - 1;
+          }
+        }
+      }
+    }
+  },
+};
diff --git a/packages/app/lib/internal/web/firebaseApp.js b/packages/app/lib/internal/web/firebaseApp.js
deleted file mode 100644
index c50cf77658..0000000000
--- a/packages/app/lib/internal/web/firebaseApp.js
+++ /dev/null
@@ -1,3 +0,0 @@
-// We need to share firebase imports between modules, otherwise
-// apps and instances of the firebase modules are not shared.
-export * from 'firebase/app';
diff --git a/packages/app/lib/internal/web/firebaseApp.ts b/packages/app/lib/internal/web/firebaseApp.ts
new file mode 100644
index 0000000000..dfbe956cad
--- /dev/null
+++ b/packages/app/lib/internal/web/firebaseApp.ts
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// We need to share firebase imports between modules, otherwise
+// apps and instances of the firebase modules are not shared.
+export * from 'firebase/app';
diff --git a/packages/app/lib/internal/web/firebaseAppCheck.js b/packages/app/lib/internal/web/firebaseAppCheck.js
deleted file mode 100644
index 455eeaf078..0000000000
--- a/packages/app/lib/internal/web/firebaseAppCheck.js
+++ /dev/null
@@ -1,6 +0,0 @@
-// We need to share firebase imports between modules, otherwise
-// apps and instances of the firebase modules are not shared.
-import 'firebase/app';
-export { getApp } from 'firebase/app';
-export * from 'firebase/app-check';
-export { makeIDBAvailable } from './memidb';
diff --git a/packages/app/lib/internal/web/firebaseAppCheck.ts b/packages/app/lib/internal/web/firebaseAppCheck.ts
new file mode 100644
index 0000000000..d4a5072f58
--- /dev/null
+++ b/packages/app/lib/internal/web/firebaseAppCheck.ts
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// We need to share firebase imports between modules, otherwise
+// apps and instances of the firebase modules are not shared.
+import 'firebase/app';
+export { getApp } from 'firebase/app';
+export * from 'firebase/app-check';
+export { makeIDBAvailable } from './memidb';
diff --git a/packages/app/lib/internal/web/firebaseAuth.js b/packages/app/lib/internal/web/firebaseAuth.js
deleted file mode 100644
index 809e1208a2..0000000000
--- a/packages/app/lib/internal/web/firebaseAuth.js
+++ /dev/null
@@ -1,4 +0,0 @@
-// We need to share firebase imports between modules, otherwise
-// apps and instances of the firebase modules are not shared.
-export * from 'firebase/app';
-export * from 'firebase/auth';
diff --git a/packages/app/lib/internal/web/firebaseAuth.ts b/packages/app/lib/internal/web/firebaseAuth.ts
new file mode 100644
index 0000000000..5091f05121
--- /dev/null
+++ b/packages/app/lib/internal/web/firebaseAuth.ts
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// We need to share firebase imports between modules, otherwise
+// apps and instances of the firebase modules are not shared.
+export * from 'firebase/app';
+export * from 'firebase/auth';
diff --git a/packages/app/lib/internal/web/firebaseDatabase.js b/packages/app/lib/internal/web/firebaseDatabase.js
deleted file mode 100644
index bf5ae640b4..0000000000
--- a/packages/app/lib/internal/web/firebaseDatabase.js
+++ /dev/null
@@ -1,4 +0,0 @@
-// We need to share firebase imports between modules, otherwise
-// apps and instances of the firebase modules are not shared.
-export * from 'firebase/app';
-export * from 'firebase/database';
diff --git a/packages/app/lib/internal/web/firebaseDatabase.ts b/packages/app/lib/internal/web/firebaseDatabase.ts
new file mode 100644
index 0000000000..4c42dc04ac
--- /dev/null
+++ b/packages/app/lib/internal/web/firebaseDatabase.ts
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// We need to share firebase imports between modules, otherwise
+// apps and instances of the firebase modules are not shared.
+export * from 'firebase/app';
+export * from 'firebase/database';
diff --git a/packages/app/lib/internal/web/firebaseFirestore.js b/packages/app/lib/internal/web/firebaseFirestore.js
deleted file mode 100644
index e3a7517966..0000000000
--- a/packages/app/lib/internal/web/firebaseFirestore.js
+++ /dev/null
@@ -1,4 +0,0 @@
-// We need to share firebase imports between modules, otherwise
-// apps and instances of the firebase modules are not shared.
-export { getApp } from 'firebase/app';
-export * from 'firebase/firestore/lite';
diff --git a/packages/app/lib/internal/web/firebaseFirestore.ts b/packages/app/lib/internal/web/firebaseFirestore.ts
new file mode 100644
index 0000000000..a07d4d488d
--- /dev/null
+++ b/packages/app/lib/internal/web/firebaseFirestore.ts
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// We need to share firebase imports between modules, otherwise
+// apps and instances of the firebase modules are not shared.
+export { getApp } from 'firebase/app';
+export * from 'firebase/firestore/lite';
diff --git a/packages/app/lib/internal/web/firebaseFunctions.js b/packages/app/lib/internal/web/firebaseFunctions.js
deleted file mode 100644
index f8e4401a14..0000000000
--- a/packages/app/lib/internal/web/firebaseFunctions.js
+++ /dev/null
@@ -1,4 +0,0 @@
-// We need to share firebase imports between modules, otherwise
-// apps and instances of the firebase modules are not shared.
-export * from 'firebase/app';
-export * from 'firebase/functions';
diff --git a/packages/app/lib/internal/web/firebaseFunctions.ts b/packages/app/lib/internal/web/firebaseFunctions.ts
new file mode 100644
index 0000000000..c8caaf81ac
--- /dev/null
+++ b/packages/app/lib/internal/web/firebaseFunctions.ts
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// We need to share firebase imports between modules, otherwise
+// apps and instances of the firebase modules are not shared.
+export * from 'firebase/app';
+export * from 'firebase/functions';
diff --git a/packages/app/lib/internal/web/firebaseInstallations.js b/packages/app/lib/internal/web/firebaseInstallations.js
deleted file mode 100644
index 9bd0a88b2e..0000000000
--- a/packages/app/lib/internal/web/firebaseInstallations.js
+++ /dev/null
@@ -1,6 +0,0 @@
-// We need to share firebase imports between modules, otherwise
-// apps and instances of the firebase modules are not shared.
-import 'firebase/app';
-export { getApp } from 'firebase/app';
-export * from 'firebase/installations';
-export { makeIDBAvailable } from './memidb';
diff --git a/packages/app/lib/internal/web/firebaseInstallations.ts b/packages/app/lib/internal/web/firebaseInstallations.ts
new file mode 100644
index 0000000000..6d9dff9dd4
--- /dev/null
+++ b/packages/app/lib/internal/web/firebaseInstallations.ts
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// We need to share firebase imports between modules, otherwise
+// apps and instances of the firebase modules are not shared.
+import 'firebase/app';
+export { getApp } from 'firebase/app';
+export * from 'firebase/installations';
+export { makeIDBAvailable } from './memidb';
diff --git a/packages/app/lib/internal/web/firebaseRemoteConfig.js b/packages/app/lib/internal/web/firebaseRemoteConfig.js
deleted file mode 100644
index 2079f29130..0000000000
--- a/packages/app/lib/internal/web/firebaseRemoteConfig.js
+++ /dev/null
@@ -1,6 +0,0 @@
-// We need to share firebase imports between modules, otherwise
-// apps and instances of the firebase modules are not shared.
-import 'firebase/app';
-export { getApp } from 'firebase/app';
-export * from 'firebase/remote-config';
-export { makeIDBAvailable } from './memidb';
diff --git a/packages/app/lib/internal/web/firebaseRemoteConfig.ts b/packages/app/lib/internal/web/firebaseRemoteConfig.ts
new file mode 100644
index 0000000000..ef71a2575d
--- /dev/null
+++ b/packages/app/lib/internal/web/firebaseRemoteConfig.ts
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// We need to share firebase imports between modules, otherwise
+// apps and instances of the firebase modules are not shared.
+import 'firebase/app';
+export { getApp } from 'firebase/app';
+export * from 'firebase/remote-config';
+export { makeIDBAvailable } from './memidb';
diff --git a/packages/app/lib/internal/web/firebaseStorage.js b/packages/app/lib/internal/web/firebaseStorage.js
deleted file mode 100644
index 143a8250cf..0000000000
--- a/packages/app/lib/internal/web/firebaseStorage.js
+++ /dev/null
@@ -1,4 +0,0 @@
-// We need to share firebase imports between modules, otherwise
-// apps and instances of the firebase modules are not shared.
-export * from 'firebase/app';
-export * from 'firebase/storage';
diff --git a/packages/app/lib/internal/web/firebaseStorage.ts b/packages/app/lib/internal/web/firebaseStorage.ts
new file mode 100644
index 0000000000..f4026e2045
--- /dev/null
+++ b/packages/app/lib/internal/web/firebaseStorage.ts
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// We need to share firebase imports between modules, otherwise
+// apps and instances of the firebase modules are not shared.
+export * from 'firebase/app';
+export * from 'firebase/storage';
diff --git a/packages/app/lib/internal/web/memidb/index.d.ts b/packages/app/lib/internal/web/memidb/index.d.ts
new file mode 100644
index 0000000000..a2b7142062
--- /dev/null
+++ b/packages/app/lib/internal/web/memidb/index.d.ts
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+/**
+ * Makes IndexedDB available in environments that don't have it
+ */
+export function makeIDBAvailable(): void;
diff --git a/packages/app/lib/internal/web/utils.js b/packages/app/lib/internal/web/utils.js
deleted file mode 100644
index 95686ec43a..0000000000
--- a/packages/app/lib/internal/web/utils.js
+++ /dev/null
@@ -1,35 +0,0 @@
-import { DeviceEventEmitter } from 'react-native';
-
-// A general purpose guard function to catch errors and return a structured error object.
-export function guard(fn) {
-  return fn().catch(e => Promise.reject(getWebError(e)));
-}
-
-// Converts a thrown error to a structured error object
-// required by RNFirebase native module internals.
-export function getWebError(error) {
-  const obj = {
-    code: error.code || 'unknown',
-    message: error.message,
-  };
-
-  // Some modules send codes as PERMISSION_DENIED, which is not
-  // the same as the Firebase error code format.
-  obj.code = obj.code.toLowerCase();
-  // Replace _ with - in code
-  obj.code = obj.code.replace(/_/g, '-');
-
-  // Split out prefix, since we internally prefix all error codes already.
-  if (obj.code.includes('/')) {
-    obj.code = obj.code.split('/')[1];
-  }
-
-  return {
-    ...obj,
-    userInfo: obj,
-  };
-}
-
-export function emitEvent(eventName, event) {
-  setImmediate(() => DeviceEventEmitter.emit('rnfb_' + eventName, event));
-}
diff --git a/packages/app/lib/internal/web/utils.ts b/packages/app/lib/internal/web/utils.ts
new file mode 100644
index 0000000000..feff92f503
--- /dev/null
+++ b/packages/app/lib/internal/web/utils.ts
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import { DeviceEventEmitter } from 'react-native';
+import { type ReactNativeFirebase } from '../../index';
+
+// A general purpose guard function to catch errors and return a structured error object.
+export function guard<T>(fn: () => Promise<T>): Promise<T> {
+  return fn().catch(e => Promise.reject(getWebError(e)));
+}
+
+// Converts a thrown error to a structured error object
+// required by RNFirebase native module internals.
+export function getWebError(
+  error: Error & { code?: string },
+): ReactNativeFirebase.NativeFirebaseError {
+  let code = error.code || 'unknown';
+
+  // Some modules send codes as PERMISSION_DENIED, which is not
+  // the same as the Firebase error code format.
+  code = code.toLowerCase();
+  // Replace _ with - in code
+  code = code.replace(/_/g, '-');
+
+  // Split out prefix, since we internally prefix all error codes already.
+  if (code.includes('/')) {
+    const parts = code.split('/');
+    code = parts[1] || code;
+  }
+
+  return {
+    code,
+    message: error.message,
+    namespace: 'app',
+    nativeErrorCode: code,
+    nativeErrorMessage: error.message,
+    name: error.name,
+  } as ReactNativeFirebase.NativeFirebaseError;
+}
+
+export function emitEvent(eventName: string, event: unknown): void {
+  setImmediate(() => DeviceEventEmitter.emit('rnfb_' + eventName, event));
+}
diff --git a/packages/app/lib/modular.ts b/packages/app/lib/modular.ts
new file mode 100644
index 0000000000..f1d101f4f5
--- /dev/null
+++ b/packages/app/lib/modular.ts
@@ -0,0 +1,200 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import { MODULAR_DEPRECATION_ARG } from './common';
+import type { ReactNativeFirebase, LogCallback, LogOptions } from './types/app';
+import {
+  deleteApp as deleteAppCompat,
+  getApp as getAppCompat,
+  getApps as getAppsCompat,
+  initializeApp as initializeAppCompat,
+  setLogLevel as setLogLevelCompat,
+  setReactNativeAsyncStorage as setReactNativeAsyncStorageCompat,
+} from './internal/registry/app';
+import { setUserLogHandler } from './internal/logger';
+import { version as sdkVersion } from './version';
+import { NativeModules } from 'react-native';
+
+/**
+ * Renders this app unusable and frees the resources of all associated services.
+ * @param app - The app to delete.
+ * @returns Promise<void>
+ */
+export function deleteApp(app: ReactNativeFirebase.FirebaseApp): Promise<void> {
+  return deleteAppCompat.call(
+    null,
+    app.name,
+    (app as any)._nativeInitialized,
+    // @ts-expect-error - Extra arg used by deprecation proxy to detect modular calls
+    MODULAR_DEPRECATION_ARG,
+  );
+}
+
+/**
+ * Registers a library's name and version for platform logging purposes.
+ * @param _libraryKeyOrName - library name or key.
+ * @param _version - library version.
+ * @param _variant - library variant. Optional.
+ * @returns Promise<void>
+ */
+export function registerVersion(
+  _libraryKeyOrName: string,
+  _version: string,
+  _variant?: string,
+): Promise<void> {
+  throw new Error('registerVersion is only supported on Web');
+}
+
+/**
+ * Sets log handler for VertexAI only currently.
+ * @param logCallback - The callback function to handle logs.
+ * @param options - Optional settings for log handling.
+ * @returns void
+ */
+export function onLog(logCallback: LogCallback | null, options?: LogOptions): void {
+  setUserLogHandler(logCallback, options);
+}
+
+/**
+ * Gets the list of all initialized apps.
+ * @returns An array of all initialized Firebase apps.
+ */
+export function getApps(): ReactNativeFirebase.FirebaseApp[] {
+  return getAppsCompat.call(
+    null,
+    // @ts-expect-error - Extra arg used by deprecation proxy to detect modular calls
+    MODULAR_DEPRECATION_ARG,
+  );
+}
+
+/**
+ * Initializes a Firebase app with the provided options and name.
+ * @param options - Options to configure the services used in the app.
+ * @param configOrName - The optional name of the app, or config for the app to initialize (a name of '[DEFAULT]' will be used if omitted).
+ * @returns The initialized Firebase app.
+ */
+export function initializeApp(
+  options: ReactNativeFirebase.FirebaseAppOptions,
+  configOrName?: string | ReactNativeFirebase.FirebaseAppConfig,
+): Promise<ReactNativeFirebase.FirebaseApp> {
+  return initializeAppCompat.call(
+    null,
+    options,
+    configOrName,
+    // @ts-expect-error - Extra arg used by deprecation proxy to detect modular calls
+    MODULAR_DEPRECATION_ARG,
+  );
+}
+
+/**
+ * Retrieves an instance of a Firebase app.
+ * @param name - The optional name of the app to return ('[DEFAULT]' if omitted).
+ * @returns The requested Firebase app instance.
+ */
+export function getApp(name?: string): ReactNativeFirebase.FirebaseApp {
+  return getAppCompat.call(
+    null,
+    name,
+    // @ts-expect-error - Extra arg used by deprecation proxy to detect modular calls
+    MODULAR_DEPRECATION_ARG,
+  );
+}
+
+/**
+ * Sets the log level across all Firebase SDKs.
+ * @param logLevel - The log level to set ('debug', 'verbose', 'info', 'warn', 'error', 'silent').
+ * @returns void
+ */
+export function setLogLevel(logLevel: ReactNativeFirebase.LogLevelString): void {
+  return setLogLevelCompat.call(
+    null,
+    logLevel,
+    // @ts-expect-error - Extra arg used by deprecation proxy to detect modular calls
+    MODULAR_DEPRECATION_ARG,
+  );
+}
+
+/**
+ * The `AsyncStorage` implementation to use for persisting data on 'Other' platforms.
+ * If not specified, in memory persistence is used.
+ *
+ * This is required if you want to persist things like Auth sessions, Analytics device IDs, etc.
+ */
+export function setReactNativeAsyncStorage(
+  asyncStorage: ReactNativeFirebase.ReactNativeAsyncStorage,
+): void {
+  return setReactNativeAsyncStorageCompat.call(
+    null,
+    asyncStorage,
+    // @ts-expect-error - Extra arg used by deprecation proxy to detect modular calls
+    MODULAR_DEPRECATION_ARG,
+  );
+}
+
+/**
+ * Gets react-native-firebase specific "meta" data from native Info.plist / AndroidManifest.xml
+ * @returns map of key / value pairs containing native meta data
+ */
+export function metaGetAll(): Promise<{ [key: string]: string | boolean }> {
+  return NativeModules.RNFBAppModule.metaGetAll();
+}
+
+/**
+ * Gets react-native-firebase specific "firebase.json" data
+ * @returns map of key / value pairs containing native firebase.json constants
+ */
+export function jsonGetAll(): Promise<{ [key: string]: string | boolean }> {
+  return NativeModules.RNFBAppModule.jsonGetAll();
+}
+
+/**
+ * Clears react-native-firebase specific native preferences
+ * @returns Promise<void>
+ */
+export function preferencesClearAll(): Promise<void> {
+  return NativeModules.RNFBAppModule.preferencesClearAll();
+}
+
+/**
+ * Gets react-native-firebase specific native preferences
+ * @returns map of key / value pairs containing native preferences data
+ */
+export function preferencesGetAll(): Promise<{ [key: string]: string | boolean }> {
+  return NativeModules.RNFBAppModule.preferencesGetAll();
+}
+
+/**
+ * Sets react-native-firebase specific native boolean preference
+ * @param key the name of the native preference to set
+ * @param value the value of the native preference to set
+ * @returns Promise<void>
+ */
+export function preferencesSetBool(key: string, value: boolean): Promise<void> {
+  return NativeModules.RNFBAppModule.preferencesSetBool(key, value);
+}
+
+/**
+ * Sets react-native-firebase specific native string preference
+ * @param key the name of the native preference to set
+ * @param value the value of the native preference to set
+ * @returns Promise<void>
+ */
+export function preferencesSetString(key: string, value: string): Promise<void> {
+  return NativeModules.RNFBAppModule.preferencesSetString(key, value);
+}
+
+export const SDK_VERSION = sdkVersion;
diff --git a/packages/app/lib/modular/index.d.ts b/packages/app/lib/modular/index.d.ts
deleted file mode 100644
index 51f6de4c54..0000000000
--- a/packages/app/lib/modular/index.d.ts
+++ /dev/null
@@ -1,133 +0,0 @@
-import { ReactNativeFirebase } from '..';
-
-type FirebaseApp = ReactNativeFirebase.FirebaseApp & {
-  functions(regionOrCustomDomain?: string): Functions;
-};
-import FirebaseAppOptions = ReactNativeFirebase.FirebaseAppOptions;
-import LogLevelString = ReactNativeFirebase.LogLevelString;
-import FirebaseAppConfig = ReactNativeFirebase.FirebaseAppConfig;
-
-/**
- * Renders this app unusable and frees the resources of all associated services.
- * @param app - FirebaseApp - The app to delete.
- * @returns Promise<void>
- */
-export function deleteApp(app: FirebaseApp): Promise<void>;
-
-/**
- * Registers a library's name and version for platform logging purposes.
- * @param libraryKeyOrName - Library name or key.
- * @param version - Library version.
- * @param variant - Library variant. Optional.
- * @returns Promise<void>
- */
-export function registerVersion(
-  libraryKeyOrName: string,
-  version: string,
-  variant?: string,
-): Promise<void>;
-
-/**
- * Sets log handler for all Firebase SDKs. Currently only supported on VertexAI.
- * @param logCallback - The callback function to handle logs.
- * @param options - Optional settings for log handling.
- * @returns <void>
- */
-
-interface LogCallbackParams {
-  level: LogLevelString;
-  message: string;
-  args: unknown[];
-  type: string;
-}
-
-export function onLog(
-  logCallback: (callbackParams: LogCallbackParams) => void,
-  options?: any,
-): void;
-
-/**
- * Gets the list of all initialized apps.
- * @returns FirebaseApp[] - An array of all initialized Firebase apps.
- */
-export function getApps(): FirebaseApp[];
-
-/**
- * Initializes a Firebase app with the provided options and name.
- * @param options - Options to configure the services used in the app.
- * @param name - The optional name of the app to initialize ('[DEFAULT]' if omitted).
- * @returns Promise<FirebaseApp> - The initialized Firebase app.
- */
-export function initializeApp(options: FirebaseAppOptions, name?: string): Promise<FirebaseApp>;
-
-/**
- * Initializes a Firebase app with the provided options and config.
- * @param options - Options to configure the services used in the app.
- * @param config - The optional config for your firebase app.
- * @returns Promise<FirebaseApp> - The initialized Firebase app.
- */
-export function initializeApp(
-  options: FirebaseAppOptions,
-  config?: FirebaseAppConfig,
-): Promise<FirebaseApp>;
-/**
- * Retrieves an instance of a Firebase app.
- * @param name - The optional name of the app to return ('[DEFAULT]' if omitted).
- * @returns FirebaseApp - The requested Firebase app instance.
- */
-export function getApp(name?: string): FirebaseApp;
-
-/**
- * Sets the log level across all Firebase SDKs.
- * @param logLevel - The log level to set ('debug', 'verbose', 'info', 'warn', 'error', 'silent').
- * @returns void
- */
-export function setLogLevel(logLevel: LogLevelString): void;
-
-/**
- * Gets react-native-firebase specific "meta" data from native Info.plist / AndroidManifest.xml
- * @returns map of key / value pairs containing native meta data
- */
-export function metaGetAll(): Promise<{ [keyof: string]: string | boolean }>;
-
-/**
- * Gets react-native-firebase specific "firebase.json" data
- * @returns map of key / value pairs containing native firebase.json constants
- */
-export function jsonGetAll(): Promise<{ [keyof: string]: string | boolean }>;
-
-/**
- * Clears react-native-firebase specific native preferences
- * @returns Promise<void>
- */
-export function preferencesClearAll(): Promise<void>;
-
-/**
- * Gets react-native-firebase specific native preferences
- * @returns map of key / value pairs containing native preferences data
- */
-export function preferencesGetAll(): Promise<{ [keyof: string]: string | boolean }>;
-
-/**
- * Sets react-native-firebase specific native boolean preference
- * @param key the name of the native preference to set
- * @param value the value of the native preference to set
- * @returns Promise<void>
- */
-export function preferencesSetBool(key: string, value: boolean): Promise<void>;
-
-/**
- * Sets react-native-firebase specific native string preference
- * @param key the name of the native preference to set
- * @param value the value of the native preference to set
- * @returns Promise<void>
- */
-export function preferencesSetString(key: string, value: string): Promise<void>;
-
-/**
- * The `AsyncStorage` implementation to use for persisting data on 'Other' platforms.
- * If not specified, in memory persistence is used.
- *
- * This is required if you want to persist things like Auth sessions, Analytics device IDs, etc.
- */
-export function setReactNativeAsyncStorage(asyncStorage: ReactNativeAsyncStorage): void;
diff --git a/packages/app/lib/modular/index.js b/packages/app/lib/modular/index.js
deleted file mode 100644
index bc485ca7f3..0000000000
--- a/packages/app/lib/modular/index.js
+++ /dev/null
@@ -1,150 +0,0 @@
-import { MODULAR_DEPRECATION_ARG } from '@react-native-firebase/app/lib/common';
-/* eslint-disable @typescript-eslint/no-unused-vars */
-import {
-  deleteApp as deleteAppCompat,
-  getApp as getAppCompat,
-  getApps as getAppsCompat,
-  initializeApp as initializeAppCompat,
-  setLogLevel as setLogLevelCompat,
-  setReactNativeAsyncStorage as setReactNativeAsyncStorageCompat,
-} from '../internal';
-import { setUserLogHandler } from '../internal/logger';
-import sdkVersion from '../version';
-
-/**
- * @typedef {import('..').ReactNativeFirebase.FirebaseApp} FirebaseApp
- * @typedef {import('..').ReactNativeFirebase.FirebaseAppOptions} FirebaseAppOptions
- * @typedef {import('..').ReactNativeFirebase.LogLevelString} LogLevelString
- * @typedef {import('../internal/logger').LogCallback} LogCallback
- * @typedef {import('../internal/logger').LogOptions} LogOptions
- */
-
-/**
- * Renders this app unusable and frees the resources of all associated services.
- * @param {FirebaseApp} app - The app to delete.
- * @returns {Promise<void>}
- */
-export function deleteApp(app) {
-  return deleteAppCompat.call(null, app.name, app._nativeInitialized, MODULAR_DEPRECATION_ARG);
-}
-
-/**
- * Registers a library's name and version for platform logging purposes.
-  @param {string} libraryKeyOrName - library name or key.
-  @param {string} version - library version.
-  @param {string | undefined} variant - library variant. Optional.
- * @returns {Promise<void>}
- */
-export function registerVersion(libraryKeyOrName, version, variant) {
-  throw new Error('registerVersion is only supported on Web');
-}
-
-/**
- * Sets log handler for VertexAI only currently.
- * @param {LogCallback | null} logCallback - The callback function to handle logs.
- * @param {LogOptions} [options] - Optional settings for log handling.
- * @returns {void}
- */
-export function onLog(logCallback, options) {
-  setUserLogHandler(logCallback, options);
-}
-
-/**
- * Gets the list of all initialized apps.
- * @returns {FirebaseApp[]} - An array of all initialized Firebase apps.
- */
-export function getApps() {
-  return getAppsCompat.call(null, MODULAR_DEPRECATION_ARG);
-}
-
-/**
- * Initializes a Firebase app with the provided options and name.
- * @param {FirebaseAppOptions} options - Options to configure the services used in the app.
- * @param {string | FirebaseAppConfig} [configOrName] - The optional name of the app, or config for the app to initialize (a name of '[DEFAULT]' will be used if omitted).
- * @returns {FirebaseApp} - The initialized Firebase app.
- */
-export function initializeApp(options, configOrName) {
-  return initializeAppCompat.call(null, options, configOrName, MODULAR_DEPRECATION_ARG);
-}
-
-/**
- * Retrieves an instance of a Firebase app.
- * @param {string} [name] - The optional name of the app to return ('[DEFAULT]' if omitted).
- * @returns {FirebaseApp} - The requested Firebase app instance.
- */
-export function getApp(name) {
-  return getAppCompat.call(null, name, MODULAR_DEPRECATION_ARG);
-}
-
-/**
- * Sets the log level across all Firebase SDKs.
- * @param {LogLevelString} logLevel - The log level to set ('debug', 'verbose', 'info', 'warn', 'error', 'silent').
- * @returns {void}
- */
-export function setLogLevel(logLevel) {
-  return setLogLevelCompat.call(null, logLevel, MODULAR_DEPRECATION_ARG);
-}
-
-/**
- * The `AsyncStorage` implementation to use for persisting data on 'Other' platforms.
- * If not specified, in memory persistence is used.
- *
- * This is required if you want to persist things like Auth sessions, Analytics device IDs, etc.
- */
-export function setReactNativeAsyncStorage(asyncStorage) {
-  return setReactNativeAsyncStorageCompat.call(null, asyncStorage, MODULAR_DEPRECATION_ARG);
-}
-
-/**
- * Gets react-native-firebase specific "meta" data from native Info.plist / AndroidManifest.xml
- * @returns map of key / value pairs containing native meta data
- */
-export function metaGetAll() {
-  return NativeModules.RNFBAppModule.metaGetAll();
-}
-
-/**
- * Gets react-native-firebase specific "firebase.json" data
- * @returns map of key / value pairs containing native firebase.json constants
- */
-export function jsonGetAll() {
-  return NativeModules.RNFBAppModule.jsonGetAll();
-}
-
-/**
- * Clears react-native-firebase specific native preferences
- * @returns Promise<void>
- */
-export function preferencesClearAll() {
-  return NativeModules.RNFBAppModule.preferencesClearAll();
-}
-
-/**
- * Gets react-native-firebase specific native preferences
- * @returns map of key / value pairs containing native preferences data
- */
-export function preferencesGetAll() {
-  return NativeModules.RNFBAppModule.preferencesGetAll();
-}
-
-/**
- * Sets react-native-firebase specific native boolean preference
- * @param key the name of the native preference to set
- * @param value the value of the native preference to set
- * @returns Promise<void>
- */
-export function preferencesSetBool(key, value) {
-  return NativeModules.RNFBAppModule.preferencesSetBool(key, value);
-}
-
-/**
- * Sets react-native-firebase specific native string preference
- * @param key the name of the native preference to set
- * @param value the value of the native preference to set
- * @returns Promise<void>
- */
-export function preferencesSetString(key, value) {
-  return NativeModules.RNFBAppModule.preferencesSetString(key, value);
-}
-
-export const SDK_VERSION = sdkVersion;
diff --git a/packages/app/lib/index.js b/packages/app/lib/namespaced.ts
similarity index 91%
rename from packages/app/lib/index.js
rename to packages/app/lib/namespaced.ts
index 17d3e2e495..6840013a3c 100644
--- a/packages/app/lib/index.js
+++ b/packages/app/lib/namespaced.ts
@@ -16,9 +16,9 @@
  */
 
 import { getFirebaseRoot } from './internal/registry/namespace';
+import utils from './utils';
 
 export const firebase = getFirebaseRoot();
-export * from './modular';
-export { default as utils } from './utils';
+export { utils };
 
 export default firebase;
diff --git a/packages/app/lib/index.d.ts b/packages/app/lib/types/app.ts
similarity index 83%
rename from packages/app/lib/index.d.ts
rename to packages/app/lib/types/app.ts
index a51dce1ad2..1c6d5ad145 100644
--- a/packages/app/lib/index.d.ts
+++ b/packages/app/lib/types/app.ts
@@ -16,20 +16,11 @@
  */
 
 /**
- * Core React Native Firebase package.
- *
- * #### Example 1
- *
- * Access the default firebase app from the `app` package:
- *
- * ```js
- * import firebase from '@react-native-firebase/app';
- *
- * console.log(firebase.app().name);
- * ```
+ * Core React Native Firebase package types.
  *
  * @firebase app
  */
+// eslint-disable-next-line @typescript-eslint/no-namespace
 export namespace ReactNativeFirebase {
   export interface NativeFirebaseError extends Error {
     /**
@@ -138,7 +129,12 @@ export namespace ReactNativeFirebase {
     automaticResourceManagement?: boolean;
   }
 
-  export interface FirebaseApp {
+  /**
+   * Base interface for FirebaseApp containing core properties and methods.
+   * The concrete FirebaseApp class implements this interface.
+   * Module-specific methods (auth(), analytics(), etc.) are added to FirebaseApp via declaration merging.
+   */
+  export interface FirebaseAppBase {
     /**
      * The name (identifier) for this App. '[DEFAULT]' is the default App.
      */
@@ -162,6 +158,19 @@ export namespace ReactNativeFirebase {
     utils(): Utils.Module;
   }
 
+  /**
+   * Full FirebaseApp interface that extends the base interface.
+   * Module-specific methods (auth(), analytics(), etc.) are added here via declaration merging
+   * from individual package .d.ts files.
+   */
+  // eslint-disable-next-line @typescript-eslint/no-empty-object-type
+  export interface FirebaseApp extends FirebaseAppBase {
+    // Module methods are added here via declaration merging, e.g.:
+    // auth(): FirebaseAuthTypes.Module;
+    // analytics(): FirebaseAnalyticsTypes.Module;
+    // etc.
+  }
+
   /**
    * Interface for a supplied `AsyncStorage`.
    */
@@ -258,27 +267,17 @@ export namespace ReactNativeFirebase {
      * and related services inside React Native, e.g. Test Lab helpers
      * and Google Play Services version helpers.
      */
-    utils: typeof utils;
+    utils: Utils.Module;
   }
 
   /**
    * A class that all React Native Firebase modules extend from to provide default behaviour.
    */
-  export class FirebaseModule {
+  export abstract class FirebaseModule {
     /**
      * The current `FirebaseApp` instance for this Firebase service.
      */
-    app: FirebaseApp;
-
-    /**
-     * The native module instance for this Firebase service.
-     */
-    private native: any;
-
-    /**
-     * Returns the shared event emitter instance used for all JS event routing.
-     */
-    private emitter: any;
+    abstract app: FirebaseApp;
   }
 
   // eslint-disable-next-line @typescript-eslint/no-empty-object-type
@@ -300,11 +299,46 @@ export namespace ReactNativeFirebase {
      */
     readonly SDK_VERSION: string;
   } & S;
+
+  /**
+   * Type for the `firebase` named export from module packages.
+   * Provides complete typing for:
+   * - Root level access: `firebase.functions(app?)`
+   * - App level access: `firebase.app().functions(region?)`
+   * - Statics: `firebase.functions.HttpsErrorCode`
+   * - Root properties: `firebase.SDK_VERSION`, `firebase.app()`, etc.
+   *
+   * @typeParam Namespace - The module namespace (e.g., 'functions', 'auth', 'firestore')
+   * @typeParam M - The module instance type (must extend FirebaseModule with `app` property)
+   * @typeParam S - The module statics type
+   * @typeParam HasCustomArg - true if app-level accessor takes optional string (region/url/databaseId)
+   *
+   * @example
+   * // In functions package:
+   * export const firebase = getFirebaseRoot() as ReactNativeFirebase.FirebaseNamespacedExport<
+   *   'functions',
+   *   FunctionsModule,
+   *   FunctionsStatics,
+   *   true  // functions() takes regionOrCustomDomain
+   * >;
+   */
+  export type FirebaseNamespacedExport<
+    Namespace extends string,
+    M extends FirebaseModule,
+    S extends object = object,
+    HasCustomArg extends boolean = false,
+  > = Module &
+    Record<Namespace, FirebaseModuleWithStaticsAndApp<M, S>> & {
+      app(
+        name?: string,
+      ): FirebaseApp & Record<Namespace, HasCustomArg extends true ? (arg?: string) => M : () => M>;
+    };
 }
 
-/*
+/**
  * @firebase utils
  */
+// eslint-disable-next-line @typescript-eslint/no-namespace
 export namespace Utils {
   import FirebaseModule = ReactNativeFirebase.FirebaseModule;
 
@@ -431,6 +465,7 @@ export namespace Utils {
   }
 
   export interface Statics {
+    SDK_VERSION: string;
     FilePath: FilePath;
   }
 
@@ -533,7 +568,7 @@ export namespace Utils {
    * const defaultAppUtils = firebase.utils();
    * ```
    */
-  export class Module extends FirebaseModule {
+  export abstract class Module extends FirebaseModule {
     /**
      * Returns true if this app is running inside a Firebase Test Lab environment.
      *
@@ -544,7 +579,7 @@ export namespace Utils {
      * ```
      * @android Android only - iOS returns false
      */
-    isRunningInTestLab: boolean;
+    abstract isRunningInTestLab: boolean;
     /**
      * Returns PlayServicesAvailability properties
      *
@@ -556,7 +591,7 @@ export namespace Utils {
      *
      * @android Android only - iOS always returns { isAvailable: true, status: 0 }
      */
-    playServicesAvailability: PlayServicesAvailability;
+    abstract playServicesAvailability: PlayServicesAvailability;
 
     /**
      * Returns PlayServicesAvailability properties
@@ -569,7 +604,7 @@ export namespace Utils {
      *
      * @android Android only - iOS always returns { isAvailable: true, status: 0 }
      */
-    getPlayServicesStatus(): Promise<PlayServicesAvailability>;
+    abstract getPlayServicesStatus(): Promise<PlayServicesAvailability>;
 
     /**
      * A prompt appears on the device to ask the user to update play services
@@ -582,7 +617,7 @@ export namespace Utils {
      *
      * @android Android only - iOS returns undefined
      */
-    promptForPlayServices(): Promise<void>;
+    abstract promptForPlayServices(): Promise<void>;
     /**
      * Attempts to make Google Play services available on this device
      *
@@ -594,7 +629,7 @@ export namespace Utils {
      *
      * @android Android only - iOS returns undefined
      */
-    makePlayServicesAvailable(): Promise<void>;
+    abstract makePlayServicesAvailable(): Promise<void>;
     /**
      * Resolves an error by starting any intents requiring user interaction.
      *
@@ -606,16 +641,22 @@ export namespace Utils {
      *
      * @android Android only - iOS returns undefined
      */
-    resolutionForPlayServices(): Promise<void>;
+    abstract resolutionForPlayServices(): Promise<void>;
   }
 }
 
-/**
- * Add Utils module as a named export for `app`.
- */
-export const utils: ReactNativeFirebase.FirebaseModuleWithStatics<Utils.Module, Utils.Statics>;
+export interface LogCallbackParams {
+  level: ReactNativeFirebase.LogLevelString;
+  message: string;
+  args: unknown[];
+  type: string;
+}
+
+export type LogCallback = (callbackParams: LogCallbackParams) => void;
 
-export * from './modular';
+export interface LogOptions {
+  level?: ReactNativeFirebase.LogLevelString;
+}
 
-declare const module: ReactNativeFirebase.Module;
-export default module;
+// Re-export FirebaseApp as a named type for easier importing
+export type FirebaseApp = ReactNativeFirebase.FirebaseApp;
diff --git a/packages/app/lib/types/internal.ts b/packages/app/lib/types/internal.ts
new file mode 100644
index 0000000000..c1999aadcc
--- /dev/null
+++ b/packages/app/lib/types/internal.ts
@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2016-present Invertase Limited & Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this library except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import type { ReactNativeFirebase, Utils } from './app';
+
+/**
+ * Internal types for React Native Firebase
+ * These types are used internally across multiple files and should not be exported to consumers
+ */
+
+/**
+ * Firebase JSON configuration from firebase.json file
+ * Structure: { "react-native": { [key: string]: boolean | string }, ... }
+ */
+export type FirebaseJsonConfig = Record<string, unknown>;
+
+/**
+ * Configuration for module namespace registration
+ */
+export interface ModuleConfig {
+  namespace: string;
+  nativeModuleName?: string | string[];
+  hasMultiAppSupport?: boolean;
+  hasCustomUrlOrRegionSupport?: boolean;
+  nativeEvents?: boolean | string[];
+  disablePrependCustomUrlOrRegion?: boolean;
+  turboModule?: boolean;
+}
+
+/**
+ * Extended configuration for namespace registration including native module details
+ */
+export interface NamespaceConfig extends ModuleConfig {
+  nativeModuleName: string | string[];
+  nativeEvents: boolean | string[];
+  // ModuleClass can be FirebaseModule or any subclass of it
+  // Uses FirebaseAppBase (the concrete class type) rather than FirebaseApp (the augmented interface)
+  ModuleClass: new (
+    app: ReactNativeFirebase.FirebaseAppBase,
+    config: ModuleConfig,
+    customUrlOrRegion?: string | null,
+  ) => ReactNativeFirebase.FirebaseModule;
+  statics?: object;
+  version?: string;
+}
+
+/**
+ * Type for a Firebase module getter function that can optionally accept
+ * a custom URL/region/databaseId parameter
+ */
+export type ModuleGetter = {
+  (customUrlOrRegionOrDatabaseId?: string): ReactNativeFirebase.FirebaseModule;
+  [key: string]: unknown;
+};
+
+/**
+ * Type for Firebase root object with module getters
+ */
+export interface FirebaseRoot {
+  initializeApp: (
+    options: ReactNativeFirebase.FirebaseAppOptions,
+    configOrName?: string | ReactNativeFirebase.FirebaseAppConfig,
+  ) => Promise<ReactNativeFirebase.FirebaseApp>;
+  setReactNativeAsyncStorage: (asyncStorage: ReactNativeFirebase.ReactNativeAsyncStorage) => void;
+  app: (name?: string) => ReactNativeFirebase.FirebaseApp;
+  apps: ReactNativeFirebase.FirebaseApp[];
+  SDK_VERSION: string;
+  setLogLevel: (logLevel: ReactNativeFirebase.LogLevelString) => void;
+  utils: Utils.Statics & (() => Utils.Module);
+  [key: string]: unknown;
+}
+
+/**
+ * Native error types
+ */
+export interface NativeErrorUserInfo {
+  code?: string;
+  message?: string;
+  nativeErrorCode?: string | number;
+  nativeErrorMessage?: string;
+  [key: string]: any;
+}
+
+export interface NativeError {
+  userInfo: NativeErrorUserInfo;
+  message?: string;
+  customData?: any;
+  operationType?: string;
+}
+
+/**
+ * AsyncStorage interface compatible with React Native AsyncStorage
+ * Internal version used by the library
+ */
+export interface AsyncStorageStatic {
+  setItem: (key: string, value: string) => Promise<void>;
+  getItem: (key: string) => Promise<string | null>;
+  removeItem: (key: string) => Promise<void>;
+}
+
+/**
+ * Common utility types
+ */
+export interface DataUrlParts {
+  base64String: string | undefined;
+  mediaType: string | undefined;
+}
+
+export interface Observer<T> {
+  next: (value: T) => void;
+  error?: (error: Error) => void;
+  complete?: () => void;
+}
+
+export interface SerializedValue {
+  type: string;
+  value: any;
+}
+
+export interface Deferred<T> {
+  promise: Promise<T>;
+  resolve: ((value: T) => void) | null;
+  reject: ((reason?: any) => void) | null;
+}
+
+export type Callback<T> =
+  | ((error: Error | null, result?: T) => void)
+  | ((error: Error | null) => void);
diff --git a/packages/app/lib/utils/UtilsStatics.js b/packages/app/lib/utils/UtilsStatics.ts
similarity index 67%
rename from packages/app/lib/utils/UtilsStatics.js
rename to packages/app/lib/utils/UtilsStatics.ts
index addbd7f394..69c9860aa6 100644
--- a/packages/app/lib/utils/UtilsStatics.js
+++ b/packages/app/lib/utils/UtilsStatics.ts
@@ -16,7 +16,9 @@
  */
 
 import { NativeModules } from 'react-native';
-import { stripTrailingSlash, isOther } from '../../lib/common';
+import { stripTrailingSlash, isOther } from '../common';
+import { Utils } from '../types/app';
+import { version } from '../version';
 
 const PATH_NAMES = [
   'MAIN_BUNDLE',
@@ -28,38 +30,44 @@ const PATH_NAMES = [
   'LIBRARY_DIRECTORY',
   'PICTURES_DIRECTORY',
   'MOVIES_DIRECTORY',
-];
+] as const;
 
-const PATH_FILE_TYPES = ['FILE_TYPE_REGULAR', 'FILE_TYPE_DIRECTORY'];
+const PATH_FILE_TYPES = ['FILE_TYPE_REGULAR', 'FILE_TYPE_DIRECTORY'] as const;
 
-const paths = {};
+const paths: Partial<Utils.FilePath> = {};
 let processedPathConstants = false;
 
-function processPathConstants(nativeModule) {
+function processPathConstants(nativeModule: any): Utils.FilePath {
   if (processedPathConstants || !nativeModule) {
-    return paths;
+    return paths as Utils.FilePath;
   }
   processedPathConstants = true;
 
   for (let i = 0; i < PATH_NAMES.length; i++) {
     const path = PATH_NAMES[i];
-    paths[path] = nativeModule[path] ? stripTrailingSlash(nativeModule[path]) : null;
+    if (path) {
+      (paths as any)[path] = nativeModule[path] ? stripTrailingSlash(nativeModule[path]) : null;
+    }
   }
 
   for (let i = 0; i < PATH_FILE_TYPES.length; i++) {
     const pathFileType = PATH_FILE_TYPES[i];
-    paths[pathFileType] = stripTrailingSlash(nativeModule[pathFileType]);
+    if (pathFileType) {
+      (paths as any)[pathFileType] = stripTrailingSlash(nativeModule[pathFileType]);
+    }
   }
 
   Object.freeze(paths);
 
-  return paths;
+  return paths as Utils.FilePath;
 }
 
-export default {
-  SDK_VERSION: require('./../version'),
-  get FilePath() {
+const statics: Utils.Statics = {
+  SDK_VERSION: version,
+  get FilePath(): Utils.FilePath {
     // We don't support path constants on non-native platforms.
     return processPathConstants(isOther ? {} : NativeModules.RNFBUtilsModule);
   },
 };
+
+export default statics;
diff --git a/packages/app/lib/utils/index.js b/packages/app/lib/utils/index.ts
similarity index 70%
rename from packages/app/lib/utils/index.js
rename to packages/app/lib/utils/index.ts
index 9f7befa923..757f0e290f 100644
--- a/packages/app/lib/utils/index.js
+++ b/packages/app/lib/utils/index.ts
@@ -15,66 +15,69 @@
  *
  */
 
-import { isIOS } from '../../lib/common';
-import { createModuleNamespace, FirebaseModule } from '../../lib/internal';
+import { isIOS } from '../common';
+import { createModuleNamespace, FirebaseModule } from '../internal';
 import UtilsStatics from './UtilsStatics';
+import { Utils } from '../types/app';
 
 const namespace = 'utils';
 const statics = UtilsStatics;
 const nativeModuleName = 'RNFBUtilsModule';
 
-class FirebaseUtilsModule extends FirebaseModule {
-  get isRunningInTestLab() {
+class FirebaseUtilsModule extends FirebaseModule<'RNFBUtilsModule'> {
+  get isRunningInTestLab(): boolean {
     if (isIOS) {
       return false;
     }
     return this.native.isRunningInTestLab;
   }
 
-  get playServicesAvailability() {
+  get playServicesAvailability(): Utils.PlayServicesAvailability {
     if (isIOS) {
       return {
         isAvailable: true,
         status: 0,
+        hasResolution: false,
+        isUserResolvableError: false,
+        error: undefined,
       };
     }
     return this.native.androidPlayServices;
   }
 
-  getPlayServicesStatus() {
+  getPlayServicesStatus(): Promise<Utils.PlayServicesAvailability> {
     if (isIOS) {
       return Promise.resolve({
         isAvailable: true,
         status: 0,
+        hasResolution: false,
+        isUserResolvableError: false,
+        error: undefined,
       });
     }
     return this.native.androidGetPlayServicesStatus();
   }
 
-  promptForPlayServices() {
+  promptForPlayServices(): Promise<void> {
     if (isIOS) {
       return Promise.resolve();
     }
     return this.native.androidPromptForPlayServices();
   }
 
-  makePlayServicesAvailable() {
+  makePlayServicesAvailable(): Promise<void> {
     if (isIOS) {
       return Promise.resolve();
     }
     return this.native.androidMakePlayServicesAvailable();
   }
 
-  resolutionForPlayServices() {
+  resolutionForPlayServices(): Promise<void> {
     if (isIOS) {
       return Promise.resolve();
     }
     return this.native.androidResolutionForPlayServices();
   }
-
-  logInfo(...args) {
-    return logger.logInfo(...args);
-  }
 }
 
 // import { utils } from '@react-native-firebase/app';
@@ -88,4 +91,4 @@ export default createModuleNamespace({
   hasMultiAppSupport: false,
   hasCustomUrlOrRegionSupport: false,
   ModuleClass: FirebaseUtilsModule,
-});
+}) as unknown as Utils.Statics & (() => Utils.Module);
diff --git a/packages/app/package.json b/packages/app/package.json
index c78429be03..83141fd50a 100644
--- a/packages/app/package.json
+++ b/packages/app/package.json
@@ -3,15 +3,17 @@
   "version": "23.7.0",
   "author": "Invertase <oss@invertase.io> (http://invertase.io)",
   "description": "A well tested, feature rich Firebase implementation for React Native, supporting iOS & Android. Individual module support for Admob, Analytics, Auth, Crash Reporting, Cloud Firestore, Database, Dynamic Links, Functions, Messaging (FCM), Remote Config, Storage and more.",
-  "main": "lib/index.js",
-  "types": "lib/index.d.ts",
+  "main": "./dist/commonjs/index.js",
+  "module": "./dist/module/index.js",
+  "types": "./dist/typescript/commonjs/lib/index.d.ts",
   "scripts": {
-    "build": "genversion --semi lib/version.js && npm run build:version",
+    "build": "genversion --esm --semi lib/version.ts && npm run build:version",
     "build:version": "node ./scripts/genversion-ios && node ./scripts/genversion-android",
     "build:clean": "rimraf android/build && rimraf ios/build",
     "build:plugin": "rimraf plugin/build && tsc --build plugin",
     "lint:plugin": "eslint plugin/src/*",
-    "prepare": "npm run build && npm run build:plugin"
+    "compile": "bob build",
+    "prepare": "npm run build && npm run build:plugin && npm run compile"
   },
   "repository": {
     "type": "git",
@@ -51,6 +53,71 @@
     "dynamic-links",
     "crashlytics"
   ],
+  "exports": {
+    ".": {
+      "source": "./lib/index.ts",
+      "import": {
+        "types": "./dist/typescript/module/lib/index.d.ts",
+        "default": "./dist/module/index.js"
+      },
+      "require": {
+        "types": "./dist/typescript/commonjs/lib/index.d.ts",
+        "default": "./dist/commonjs/index.js"
+      }
+    },
+    "./lib/internal": {
+      "source": "./lib/internal/index.ts",
+      "import": {
+        "types": "./dist/typescript/module/lib/internal/index.d.ts",
+        "default": "./dist/module/internal/index.js"
+      },
+      "require": {
+        "types": "./dist/typescript/commonjs/lib/internal/index.d.ts",
+        "default": "./dist/commonjs/internal/index.js"
+      }
+    },
+    "./lib/internal/*": {
+      "source": "./lib/internal/*.ts",
+      "import": {
+        "types": "./dist/typescript/module/lib/internal/*.d.ts",
+        "default": "./dist/module/internal/*"
+      },
+      "require": {
+        "types": "./dist/typescript/commonjs/lib/internal/*.d.ts",
+        "default": "./dist/commonjs/internal/*"
+      }
+    },
+    "./lib/common": {
+      "source": "./lib/common/index.ts",
+      "import": {
+        "types": "./dist/typescript/module/lib/common/index.d.ts",
+        "default": "./dist/module/common/index.js"
+      },
+      "require": {
+        "types": "./dist/typescript/commonjs/lib/common/index.d.ts",
+        "default": "./dist/commonjs/common/index.js"
+      }
+    },
+    "./lib/common/*": {
+      "source": "./lib/common/*.ts",
+      "import": {
+        "types": "./dist/typescript/module/lib/common/*.d.ts",
+        "default": "./dist/module/common/*"
+      },
+      "require": {
+        "types": "./dist/typescript/commonjs/lib/common/*.d.ts",
+        "default": "./dist/commonjs/common/*"
+      }
+    },
+    "./package.json": "./package.json"
+  },
+  "files": [
+    "lib",
+    "dist",
+    "!**/__tests__",
+    "!**/__fixtures__",
+    "!**/__mocks__"
+  ],
   "peerDependencies": {
     "expo": ">=47.0.0",
     "react": "*",
@@ -61,7 +128,8 @@
   },
   "devDependencies": {
     "@react-native-async-storage/async-storage": "^2.2.0",
-    "expo": "^54.0.27"
+    "expo": "^54.0.27",
+    "react-native-builder-bob": "^0.40.13"
   },
   "peerDependenciesMeta": {
     "expo": {
@@ -90,5 +158,34 @@
       "playServicesAuth": "21.4.0",
       "firebaseAppDistributionGradle": "5.2.0"
     }
-  }
+  },
+  "react-native-builder-bob": {
+    "source": "lib",
+    "output": "dist",
+    "exclude": "**/*.d.ts",
+    "targets": [
+      [
+        "module",
+        {
+          "esm": true
+        }
+      ],
+      [
+        "commonjs",
+        {
+          "esm": true
+        }
+      ],
+      [
+        "typescript",
+        {
+          "tsc": "../../node_modules/.bin/tsc"
+        }
+      ]
+    ]
+  },
+  "eslintIgnore": [
+    "node_modules/",
+    "dist/"
+  ]
 }
diff --git a/packages/app/scripts/genversion-android.js b/packages/app/scripts/genversion-android.js
index ccda19ed0a..12af85b744 100644
--- a/packages/app/scripts/genversion-android.js
+++ b/packages/app/scripts/genversion-android.js
@@ -1,7 +1,15 @@
 const fs = require('fs');
 const path = require('path');
 
-const version = require('../lib/version');
+// Read version from TypeScript file
+const versionFilePath = path.resolve(__dirname, '..', 'lib', 'version.ts');
+const versionFileContent = fs.readFileSync(versionFilePath, 'utf8');
+const versionMatch = versionFileContent.match(/version = ['"](.+?)['"]/);
+if (!versionMatch) {
+  throw new Error('Could not extract version from version.ts');
+}
+const version = versionMatch[1];
+
 const outputPath = path.resolve(
   __dirname,
   '..',
diff --git a/packages/app/scripts/genversion-ios.js b/packages/app/scripts/genversion-ios.js
index 6292b7f264..049c6cb73e 100644
--- a/packages/app/scripts/genversion-ios.js
+++ b/packages/app/scripts/genversion-ios.js
@@ -1,7 +1,15 @@
 const fs = require('fs');
 const path = require('path');
 
-const version = require('../lib/version');
+// Read version from TypeScript file
+const versionFilePath = path.resolve(__dirname, '..', 'lib', 'version.ts');
+const versionFileContent = fs.readFileSync(versionFilePath, 'utf8');
+const versionMatch = versionFileContent.match(/version = ['"](.+?)['"]/);
+if (!versionMatch) {
+  throw new Error('Could not extract version from version.ts');
+}
+const version = versionMatch[1];
+
 const outputPath = path.resolve(__dirname, '..', 'ios', 'RNFBApp', 'RNFBVersion.m');
 const template = `/**
  * Copyright (c) 2016-present Invertase Limited & Contributors
diff --git a/packages/app/tsconfig.json b/packages/app/tsconfig.json
new file mode 100644
index 0000000000..33babab5a8
--- /dev/null
+++ b/packages/app/tsconfig.json
@@ -0,0 +1,28 @@
+{
+  "compilerOptions": {
+    "allowUnreachableCode": false,
+    "allowUnusedLabels": false,
+    "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
+    "jsx": "react-jsx",
+    "lib": ["ESNext", "DOM"],
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "noFallthroughCasesInSwitch": true,
+    "noImplicitReturns": true,
+    "noImplicitUseStrict": false,
+    "noStrictGenericChecks": false,
+    "noUncheckedIndexedAccess": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "resolveJsonModule": true,
+    "skipLibCheck": true,
+    "strict": true,
+    "target": "ESNext",
+    "verbatimModuleSyntax": true,
+    "baseUrl": ".",
+    "rootDir": "."
+  },
+  "include": ["lib/**/*"],
+  "exclude": ["node_modules", "dist", "__tests__", "**/*.test.ts"]
+}
diff --git a/packages/app/type-test.ts b/packages/app/type-test.ts
index 618a15db0d..37b009fa85 100644
--- a/packages/app/type-test.ts
+++ b/packages/app/type-test.ts
@@ -19,6 +19,8 @@ import firebase, { utils } from '.';
 // checks module exists at root
 console.log(firebase.utils().app.name);
 console.log(utils().app.name);
+console.log(firebase.app().name);
+console.log(firebase.app('foo').name);
 
 // checks module exists at app level
 console.log(firebase.app().utils().app.name);
@@ -32,5 +34,18 @@ console.log(utils.FilePath.CACHES_DIRECTORY);
 console.log(firebase.utils.FilePath.CACHES_DIRECTORY);
 console.log(utils.FilePath.CACHES_DIRECTORY);
 
+// initialize app variants
+firebase.initializeApp({ apiKey: 'a', appId: 'b', projectId: 'c' });
+firebase.initializeApp({ apiKey: 'a', appId: 'b', projectId: 'c' }, 'foo');
+
+// utils instance API
+const u = firebase.utils();
+console.log(u.isRunningInTestLab);
+console.log(u.playServicesAvailability);
+u.getPlayServicesStatus();
+u.promptForPlayServices();
+u.makePlayServicesAvailable();
+u.resolutionForPlayServices();
+
 // checks root exists
 console.log(firebase.SDK_VERSION);
diff --git a/packages/database/__tests__/database.test.ts b/packages/database/__tests__/database.test.ts
index 96005442e8..4d61a55903 100644
--- a/packages/database/__tests__/database.test.ts
+++ b/packages/database/__tests__/database.test.ts
@@ -53,8 +53,6 @@ import {
   createCheckV9Deprecation,
   CheckV9DeprecationFunction,
 } from '../../app/lib/common/unitTestUtils';
-
-// @ts-ignore test
 import FirebaseModule from '../../app/lib/internal/FirebaseModule';
 
 describe('Database', function () {
@@ -303,38 +301,56 @@ describe('Database', function () {
       staticsV9Deprecation = createCheckV9Deprecation(['database', 'statics']);
       referenceV9Deprecation = createCheckV9Deprecation(['database', 'DatabaseReference']);
       // @ts-ignore test
-      jest.spyOn(FirebaseModule.prototype, 'native', 'get').mockImplementation(() => {
-        return new Proxy(
-          {},
-          {
-            get: (_target, prop) => {
-              if (prop === 'constants') {
-                return {
-                  isDatabaseCollectionEnabled: true,
-                  url: 'https://test.firebaseio.com',
-                  ref: 'ref()',
-                };
-              }
-              // Mock the once method to return proper snapshot data
-              if (prop === 'once') {
-                return jest.fn().mockResolvedValue({
-                  key: 'test',
-                  value: 'mock_value',
-                  exists: true,
-                  childKeys: [],
-                  priority: null,
-                } as never);
-              }
-              return jest.fn().mockResolvedValue({
-                constants: {
-                  isDatabaseCollectionEnabled: true,
-                  url: 'https://test.firebaseio.com',
-                },
-              } as never);
-            },
+      jest.spyOn(FirebaseModule.prototype, 'native', 'get').mockReturnValue({
+        constants: {
+          isDatabaseCollectionEnabled: true,
+          url: 'https://test.firebaseio.com',
+          ref: 'ref()',
+        },
+        on: jest.fn(),
+        off: jest.fn(),
+        once: jest.fn(
+          (_appName: any, _customUrl: any, path: any, _modifiers: any, eventType: any) => {
+            // Database native methods receive (appName, customUrlOrRegion, ...actualArgs)
+            let key = 'test';
+            if (path && typeof path === 'string') {
+              const parts = path.split('/').filter(p => p);
+              key = parts[parts.length - 1] || 'test';
+            }
+
+            const snapshotData = {
+              key,
+              value: 'mock_value',
+              exists: true,
+              childKeys: [],
+              priority: null,
+            };
+
+            if (eventType === 'value') {
+              return Promise.resolve(snapshotData);
+            }
+
+            return Promise.resolve({
+              snapshot: snapshotData,
+              previousChildName: null,
+            });
           },
-        );
-      });
+        ),
+        set: jest.fn(() => Promise.resolve()),
+        update: jest.fn(() => Promise.resolve()),
+        setWithPriority: jest.fn(() => Promise.resolve()),
+        remove: jest.fn(() => Promise.resolve()),
+        setPriority: jest.fn(() => Promise.resolve()),
+        keepSynced: jest.fn(() => Promise.resolve()),
+        transactionStart: jest.fn(() => Promise.resolve()),
+        transactionTryCommit: jest.fn(() => Promise.resolve()),
+        goOnline: jest.fn(() => Promise.resolve()),
+        goOffline: jest.fn(() => Promise.resolve()),
+        setPersistenceEnabled: jest.fn(() => Promise.resolve()),
+        setLoggingEnabled: jest.fn(() => Promise.resolve()),
+        setPersistenceCacheSizeBytes: jest.fn(() => Promise.resolve()),
+        getServerTime: jest.fn(() => Promise.resolve(Date.now())),
+      } as any);
     });
 
     it('useEmulator', function () {
diff --git a/packages/firestore/__tests__/firestore.test.ts b/packages/firestore/__tests__/firestore.test.ts
index b408478d35..29e6bf2172 100644
--- a/packages/firestore/__tests__/firestore.test.ts
+++ b/packages/firestore/__tests__/firestore.test.ts
@@ -778,21 +778,27 @@ describe('Firestore', function () {
 
       timestampV9Deprecation = createCheckV9Deprecation(['firestore', 'FirestoreTimestamp']);
 
-      // @ts-ignore test
-      jest.spyOn(FirebaseModule.prototype, 'native', 'get').mockImplementation(() => {
-        return new Proxy(
-          {},
-          {
-            get: () =>
-              jest.fn().mockResolvedValue({
-                source: 'cache',
-                changes: [],
-                documents: [],
-                metadata: {},
-                path: 'foo',
-              } as never),
-          },
-        );
+      // Mock the native module directly to avoid getter caching issues
+      const mockNative = new Proxy(
+        {},
+        {
+          get: () =>
+            (jest.fn() as any).mockResolvedValue({
+              source: 'cache',
+              changes: [],
+              documents: [],
+              metadata: {},
+              path: 'foo',
+            }),
+        },
+      );
+
+      // Override the native getter on FirebaseModule prototype
+      Object.defineProperty(FirebaseModule.prototype, 'native', {
+        get: function () {
+          return mockNative;
+        },
+        configurable: true,
       });
 
       jest
diff --git a/packages/functions/lib/HttpsError.ts b/packages/functions/lib/HttpsError.ts
index 5f5cd392dd..1a4650021f 100644
--- a/packages/functions/lib/HttpsError.ts
+++ b/packages/functions/lib/HttpsError.ts
@@ -56,7 +56,7 @@ export class HttpsError extends Error {
 
     this.stack = NativeFirebaseError.getStackWithMessage(
       `Error: ${message}`,
-      nativeErrorInstance?.jsStack,
+      nativeErrorInstance?.jsStack as string,
     );
   }
 }
diff --git a/packages/functions/lib/index.ts b/packages/functions/lib/index.ts
index b19d1bb60b..1195a5f45b 100644
--- a/packages/functions/lib/index.ts
+++ b/packages/functions/lib/index.ts
@@ -22,6 +22,7 @@ export type {
   FunctionsModule,
   Functions,
   FirebaseApp,
+  FirebaseFunctionsTypes,
 } from './types/functions';
 
 // Export modular API functions
diff --git a/packages/functions/lib/namespaced.ts b/packages/functions/lib/namespaced.ts
index 857597108e..f4b7a26623 100644
--- a/packages/functions/lib/namespaced.ts
+++ b/packages/functions/lib/namespaced.ts
@@ -25,8 +25,8 @@ import { HttpsError, type NativeError } from './HttpsError';
 import { version } from './version';
 import { setReactNativeModule } from '@react-native-firebase/app/lib/internal/nativeModule';
 import fallBackModule from './web/RNFBFunctionsModule';
-import type { HttpsCallableOptions } from './types/functions';
-import type { FirebaseApp } from '@react-native-firebase/app';
+import type { HttpsCallableOptions, FunctionsModule, FunctionsStatics } from './types/functions';
+import type { ReactNativeFirebase } from '@react-native-firebase/app';
 const namespace = 'functions';
 
 const nativeModuleName = 'NativeRNFBTurboFunctions';
@@ -75,88 +75,16 @@ const statics = {
   HttpsErrorCode,
 };
 
-// Export the complete FirebaseFunctionsTypes namespace
-// eslint-disable-next-line @typescript-eslint/no-namespace
-export namespace FirebaseFunctionsTypes {
-  export type FunctionsErrorCode =
-    | 'ok'
-    | 'cancelled'
-    | 'unknown'
-    | 'invalid-argument'
-    | 'deadline-exceeded'
-    | 'not-found'
-    | 'already-exists'
-    | 'permission-denied'
-    | 'resource-exhausted'
-    | 'failed-precondition'
-    | 'aborted'
-    | 'out-of-range'
-    | 'unimplemented'
-    | 'internal'
-    | 'unavailable'
-    | 'data-loss'
-    | 'unauthenticated';
-
-  export interface HttpsCallableResult<ResponseData = unknown> {
-    readonly data: ResponseData;
-  }
-
-  export interface HttpsCallable<RequestData = unknown, ResponseData = unknown> {
-    (data?: RequestData | null): Promise<HttpsCallableResult<ResponseData>>;
-  }
-
-  // Re-export HttpsCallableOptions from types/functions
-  export type HttpsCallableOptions = import('./types/functions').HttpsCallableOptions;
-
-  export interface HttpsError extends Error {
-    readonly code: FunctionsErrorCode;
-    readonly details?: any;
-  }
-
-  export interface HttpsErrorCode {
-    OK: 'ok';
-    CANCELLED: 'cancelled';
-    UNKNOWN: 'unknown';
-    INVALID_ARGUMENT: 'invalid-argument';
-    DEADLINE_EXCEEDED: 'deadline-exceeded';
-    NOT_FOUND: 'not-found';
-    ALREADY_EXISTS: 'already-exists';
-    PERMISSION_DENIED: 'permission-denied';
-    UNAUTHENTICATED: 'unauthenticated';
-    RESOURCE_EXHAUSTED: 'resource-exhausted';
-    FAILED_PRECONDITION: 'failed-precondition';
-    ABORTED: 'aborted';
-    OUT_OF_RANGE: 'out-of-range';
-    UNIMPLEMENTED: 'unimplemented';
-    INTERNAL: 'internal';
-    UNAVAILABLE: 'unavailable';
-    DATA_LOSS: 'data-loss';
-  }
-
-  export interface Statics {
-    HttpsErrorCode: HttpsErrorCode;
-  }
-
-  export interface Module {
-    httpsCallable<RequestData = unknown, ResponseData = unknown>(
-      name: string,
-      options?: HttpsCallableOptions,
-    ): HttpsCallable<RequestData, ResponseData>;
-    httpsCallableFromUrl<RequestData = unknown, ResponseData = unknown>(
-      url: string,
-      options?: HttpsCallableOptions,
-    ): HttpsCallable<RequestData, ResponseData>;
-    useFunctionsEmulator(origin: string): void;
-    useEmulator(host: string, port: number): void;
-  }
-}
-
 class FirebaseFunctionsModule extends FirebaseModule {
   _customUrlOrRegion: string;
   private _useFunctionsEmulatorHost: string | null;
   private _useFunctionsEmulatorPort: number;
-  // TODO: config is app package (FirebaseModule) object to be typed in the future
-  constructor(app: FirebaseApp, config: any, customUrlOrRegion: string | null) {
+
+  constructor(
+    app: ReactNativeFirebase.FirebaseAppBase,
+    config: any,
+    customUrlOrRegion?: string | null,
+  ) {
     super(app, config, customUrlOrRegion);
     this._customUrlOrRegion = customUrlOrRegion || 'us-central1';
     this._useFunctionsEmulatorHost = null;
@@ -273,9 +201,7 @@ class FirebaseFunctionsModule extends FirebaseModule {
 // import { SDK_VERSION } from '@react-native-firebase/functions';
 export const SDK_VERSION = version;
 
-// import functions from '@react-native-firebase/functions';
-// functions().logEvent(...);
-export default createModuleNamespace({
+const functionsNamespace = createModuleNamespace({
   statics,
   version,
   namespace,
@@ -287,10 +213,29 @@ export default createModuleNamespace({
   turboModule: true,
 });
 
+type FunctionsNamespace = ReactNativeFirebase.FirebaseModuleWithStaticsAndApp<
+  FunctionsModule,
+  FunctionsStatics
+> & {
+  functions: ReactNativeFirebase.FirebaseModuleWithStaticsAndApp<FunctionsModule, FunctionsStatics>;
+  firebase: ReactNativeFirebase.Module;
+  app(name?: string): ReactNativeFirebase.FirebaseApp;
+};
+
+// import functions from '@react-native-firebase/functions';
+// functions().httpsCallable(...);
+export default functionsNamespace as unknown as FunctionsNamespace;
+
 // import functions, { firebase } from '@react-native-firebase/functions';
-// functions().logEvent(...);
-// firebase.functions().logEvent(...);
-export const firebase = getFirebaseRoot();
+// functions().httpsCallable(...);
+// firebase.functions().httpsCallable(...);
+export const firebase =
+  getFirebaseRoot() as unknown as ReactNativeFirebase.FirebaseNamespacedExport<
+    'functions',
+    FunctionsModule,
+    FunctionsStatics,
+    true
+  >;
 
 // Register the interop module for non-native platforms.
 setReactNativeModule(nativeModuleName, fallBackModule);
diff --git a/packages/functions/lib/types.d.ts b/packages/functions/lib/types.d.ts
deleted file mode 100644
index 7e6520ecfc..0000000000
--- a/packages/functions/lib/types.d.ts
+++ /dev/null
@@ -1,58 +0,0 @@
-declare module '@react-native-firebase/app/lib/common' {
-  export const MODULAR_DEPRECATION_ARG: string;
-  export const isAndroid: boolean;
-  export const isNumber: (value: any) => value is number;
-}
-
-declare module '@react-native-firebase/app/lib/internal' {
-  export function createModuleNamespace(config: any): any;
-  export class FirebaseModule {
-    constructor(...args: any[]);
-    native: any;
-    firebaseJson: any;
-    _customUrlOrRegion: string | null;
-  }
-  export function getFirebaseRoot(): any;
-  export class NativeFirebaseError {
-    static getStackWithMessage(message: string, jsStack?: string): string;
-  }
-}
-
-declare module '@react-native-firebase/app/lib/internal/nativeModule' {
-  export function setReactNativeModule(moduleName: string, module: any): void;
-}
-
-declare module '@react-native-firebase/app/lib' {
-  namespace ReactNativeFirebase {
-    import FirebaseModuleWithStaticsAndApp = ReactNativeFirebase.FirebaseModuleWithStaticsAndApp;
-    interface Module {
-      functions: FirebaseModuleWithStaticsAndApp<any, any>;
-    }
-    interface FirebaseApp {
-      functions(customUrlOrRegion?: string): any;
-      readonly name: string;
-    }
-  }
-}
-
-declare module '@react-native-firebase/app/lib/internal/web/firebaseFunctions' {
-  export function getApp(appName: string): any;
-  export function getFunctions(app: any, regionOrCustomDomain?: string): any;
-  export function httpsCallable(functionsInstance: any, name: string, options?: any): any;
-  export function httpsCallableFromURL(functionsInstance: any, url: string, options?: any): any;
-  export function connectFunctionsEmulator(
-    functionsInstance: any,
-    host: string,
-    port: number,
-  ): void;
-}
-
-declare module './version' {
-  const version: string;
-  export default version;
-}
-
-declare module './web/RNFBFunctionsModule' {
-  const fallBackModule: any;
-  export default fallBackModule;
-}
diff --git a/packages/functions/lib/types/functions.ts b/packages/functions/lib/types/functions.ts
index 16463d1b62..ca437d4ad4 100644
--- a/packages/functions/lib/types/functions.ts
+++ b/packages/functions/lib/types/functions.ts
@@ -17,28 +17,213 @@
 
 import type { ReactNativeFirebase } from '@react-native-firebase/app';
 
+// ============ Options & Result Types ============
+
 export interface HttpsCallableOptions {
   timeout?: number;
 }
 
+export interface HttpsCallableResult<ResponseData = unknown> {
+  readonly data: ResponseData;
+}
+
 export interface HttpsCallable<RequestData = unknown, ResponseData = unknown> {
-  (data?: RequestData | null): Promise<{ data: ResponseData }>;
+  (data?: RequestData | null): Promise<HttpsCallableResult<ResponseData>>;
+}
+
+// ============ Error Code Types ============
+
+export type FunctionsErrorCode =
+  | 'ok'
+  | 'cancelled'
+  | 'unknown'
+  | 'invalid-argument'
+  | 'deadline-exceeded'
+  | 'not-found'
+  | 'already-exists'
+  | 'permission-denied'
+  | 'resource-exhausted'
+  | 'failed-precondition'
+  | 'aborted'
+  | 'out-of-range'
+  | 'unimplemented'
+  | 'internal'
+  | 'unavailable'
+  | 'data-loss'
+  | 'unauthenticated'
+  | 'unsupported-type'
+  | 'failed-to-parse-wrapped-number';
+
+export interface HttpsErrorCode {
+  OK: 'ok';
+  CANCELLED: 'cancelled';
+  UNKNOWN: 'unknown';
+  INVALID_ARGUMENT: 'invalid-argument';
+  DEADLINE_EXCEEDED: 'deadline-exceeded';
+  NOT_FOUND: 'not-found';
+  ALREADY_EXISTS: 'already-exists';
+  PERMISSION_DENIED: 'permission-denied';
+  UNAUTHENTICATED: 'unauthenticated';
+  RESOURCE_EXHAUSTED: 'resource-exhausted';
+  FAILED_PRECONDITION: 'failed-precondition';
+  ABORTED: 'aborted';
+  OUT_OF_RANGE: 'out-of-range';
+  UNIMPLEMENTED: 'unimplemented';
+  INTERNAL: 'internal';
+  UNAVAILABLE: 'unavailable';
+  DATA_LOSS: 'data-loss';
+  UNSUPPORTED_TYPE: 'unsupported-type';
+  FAILED_TO_PARSE_WRAPPED_NUMBER: 'failed-to-parse-wrapped-number';
+}
+
+export interface HttpsError extends Error {
+  readonly code: FunctionsErrorCode;
+  readonly details?: unknown;
 }
 
-export interface FunctionsModule {
+// ============ Module Interface ============
+
+/**
+ * Functions module instance - returned from firebase.functions() or firebase.app().functions()
+ */
+export interface FunctionsModule extends ReactNativeFirebase.FirebaseModule {
+  /** The FirebaseApp this module is associated with */
+  app: ReactNativeFirebase.FirebaseApp;
+
+  /**
+   * Returns a reference to the callable HTTPS trigger with the given name.
+   *
+   * @param name The name of the trigger.
+   * @param options Optional settings for the callable function.
+   */
   httpsCallable<RequestData = unknown, ResponseData = unknown>(
     name: string,
     options?: HttpsCallableOptions,
   ): HttpsCallable<RequestData, ResponseData>;
+
+  /**
+   * Returns a reference to the callable HTTPS trigger with the given URL.
+   *
+   * @param url The URL of the trigger.
+   * @param options Optional settings for the callable function.
+   */
   httpsCallableFromUrl<RequestData = unknown, ResponseData = unknown>(
     url: string,
     options?: HttpsCallableOptions,
   ): HttpsCallable<RequestData, ResponseData>;
+
+  /**
+   * Changes this instance to point to a Cloud Functions emulator running locally.
+   *
+   * @deprecated Use useEmulator(host, port) instead.
+   * @param origin The origin of the local emulator, e.g. "http://localhost:5001".
+   */
   useFunctionsEmulator(origin: string): void;
+
+  /**
+   * Changes this instance to point to a Cloud Functions emulator running locally.
+   *
+   * @param host The host of the emulator, e.g. "localhost" or "10.0.2.2" for Android.
+   * @param port The port of the emulator, e.g. 5001.
+   */
   useEmulator(host: string, port: number): void;
 }
 
+// ============ Statics Interface ============
+
+/**
+ * Static properties available on firebase.functions
+ */
+export interface FunctionsStatics {
+  HttpsErrorCode: HttpsErrorCode;
+}
+
+// ============ Type Aliases for Convenience ============
+
 export type Functions = FunctionsModule;
-export type FirebaseApp = ReactNativeFirebase.FirebaseApp & {
-  functions(regionOrCustomDomain?: string): Functions;
-};
+
+/**
+ * FirebaseApp type with functions() method.
+ * @deprecated Import FirebaseApp from '@react-native-firebase/app' instead.
+ * The functions() method is added via module augmentation.
+ */
+export type FirebaseApp = ReactNativeFirebase.FirebaseApp;
+
+// ============ Module Augmentation ============
+
+/* eslint-disable @typescript-eslint/no-namespace */
+declare module '@react-native-firebase/app' {
+  namespace ReactNativeFirebase {
+    interface Module {
+      functions: FirebaseModuleWithStaticsAndApp<FunctionsModule, FunctionsStatics>;
+    }
+    interface FirebaseApp {
+      functions(regionOrCustomDomain?: string): FunctionsModule;
+    }
+  }
+}
+/* eslint-enable @typescript-eslint/no-namespace */
+
+// ============ Backwards Compatibility Namespace ============
+
+/**
+ * @deprecated Use the exported types directly instead.
+ * FirebaseFunctionsTypes namespace is kept for backwards compatibility.
+ */
+/* eslint-disable @typescript-eslint/no-namespace */
+export namespace FirebaseFunctionsTypes {
+  // Short name aliases referencing top-level types
+  export type ErrorCode = FunctionsErrorCode;
+  export type CallableResult<ResponseData = unknown> = HttpsCallableResult<ResponseData>;
+  export type Callable<RequestData = unknown, ResponseData = unknown> = HttpsCallable<
+    RequestData,
+    ResponseData
+  >;
+  export type CallableOptions = HttpsCallableOptions;
+  export type Error = HttpsError;
+  export type ErrorCodeMap = HttpsErrorCode;
+  export type Statics = FunctionsStatics;
+  export type Module = FunctionsModule;
+}
+
+// Separate namespace block for Https* aliases to avoid naming conflicts
+// These provide backwards compatibility for code using FirebaseFunctionsTypes.HttpsCallableResult
+export namespace FirebaseFunctionsTypes {
+  // These must be inline definitions since TypeScript doesn't allow re-exporting
+  // with the same name as a type that already exists in scope
+  export interface HttpsCallableResult<T = unknown> {
+    readonly data: T;
+  }
+  export interface HttpsCallable<RequestData = unknown, ResponseData = unknown> {
+    (data?: RequestData | null): Promise<HttpsCallableResult<ResponseData>>;
+  }
+  export interface HttpsCallableOptions {
+    timeout?: number;
+  }
+  export interface HttpsError extends globalThis.Error {
+    readonly code: FunctionsErrorCode;
+    readonly details?: unknown;
+  }
+  export interface HttpsErrorCode {
+    OK: 'ok';
+    CANCELLED: 'cancelled';
+    UNKNOWN: 'unknown';
+    INVALID_ARGUMENT: 'invalid-argument';
+    DEADLINE_EXCEEDED: 'deadline-exceeded';
+    NOT_FOUND: 'not-found';
+    ALREADY_EXISTS: 'already-exists';
+    PERMISSION_DENIED: 'permission-denied';
+    UNAUTHENTICATED: 'unauthenticated';
+    RESOURCE_EXHAUSTED: 'resource-exhausted';
+    FAILED_PRECONDITION: 'failed-precondition';
+    ABORTED: 'aborted';
+    OUT_OF_RANGE: 'out-of-range';
+    UNIMPLEMENTED: 'unimplemented';
+    INTERNAL: 'internal';
+    UNAVAILABLE: 'unavailable';
+    DATA_LOSS: 'data-loss';
+    UNSUPPORTED_TYPE: 'unsupported-type';
+    FAILED_TO_PARSE_WRAPPED_NUMBER: 'failed-to-parse-wrapped-number';
+  }
+}
+/* eslint-enable @typescript-eslint/no-namespace */
diff --git a/packages/functions/lib/web/RNFBFunctionsModule.ts b/packages/functions/lib/web/RNFBFunctionsModule.ts
index 7d4b7b397d..989ca52120 100644
--- a/packages/functions/lib/web/RNFBFunctionsModule.ts
+++ b/packages/functions/lib/web/RNFBFunctionsModule.ts
@@ -60,7 +60,7 @@ export default {
       if (host) {
         connectFunctionsEmulator(functionsInstance, host, port);
         // Hack to work around emulator origin not being set on the instance.
-        functionsInstance.emulatorOrigin = `http://${host}:${port}`;
+        (functionsInstance as any).emulatorOrigin = `http://${host}:${port}`;
       }
       let callable;
       if (Object.keys(options).length) {
@@ -125,7 +125,7 @@ export default {
       if (host) {
         connectFunctionsEmulator(functionsInstance, host, port);
         // Hack to work around emulator origin not being set on the instance.
-        functionsInstance.emulatorOrigin = `http://${host}:${port}`;
+        (functionsInstance as any).emulatorOrigin = `http://${host}:${port}`;
       }
       const callable = httpsCallableFromURL(functionsInstance, url, options);
       const result = await callable(wrapper['data']);
diff --git a/packages/functions/tsconfig.json b/packages/functions/tsconfig.json
index 8bf433ac43..ea2ec9d3f5 100644
--- a/packages/functions/tsconfig.json
+++ b/packages/functions/tsconfig.json
@@ -5,9 +5,7 @@
     "esModuleInterop": true,
     "forceConsistentCasingInFileNames": true,
     "jsx": "react-jsx",
-    "lib": [
-      "ESNext"
-    ],
+    "lib": ["ESNext"],
     "module": "ESNext",
     "moduleResolution": "bundler",
     "noFallthroughCasesInSwitch": true,
@@ -25,7 +23,16 @@
     "baseUrl": ".",
     "rootDir": ".",
     "paths": {
-      "@react-native-firebase/app": ["../app/lib"]
+      "@react-native-firebase/app/lib/common/*": ["../app/dist/typescript/commonjs/lib/common/*"],
+      "@react-native-firebase/app/lib/common": ["../app/dist/typescript/commonjs/lib/common"],
+      "@react-native-firebase/app/lib/internal/web/*": [
+        "../app/dist/typescript/commonjs/lib/internal/web/*"
+      ],
+      "@react-native-firebase/app/lib/internal/*": [
+        "../app/dist/typescript/commonjs/lib/internal/*"
+      ],
+      "@react-native-firebase/app/lib/internal": ["../app/dist/typescript/commonjs/lib/internal"],
+      "@react-native-firebase/app": ["../app/dist/typescript/commonjs/lib"]
     }
   },
   "include": ["lib/**/*"],
diff --git a/packages/functions/type-test.ts b/packages/functions/type-test.ts
new file mode 100644
index 0000000000..0bc392bb21
--- /dev/null
+++ b/packages/functions/type-test.ts
@@ -0,0 +1,43 @@
+import functions, { firebase, FirebaseFunctionsTypes } from '.';
+
+console.log(functions().app);
+
+// checks module exists at root
+console.log(firebase.functions().app.name);
+
+// checks module exists at app level
+console.log(firebase.app().functions().app.name);
+
+// app level module accepts string arg
+console.log(firebase.app().functions('some-string').app.name);
+console.log(firebase.app().functions('some-string').httpsCallable('foo'));
+
+// checks statics exist
+console.log(firebase.functions.SDK_VERSION);
+
+// checks statics exist on defaultExport
+console.log(functions.firebase.SDK_VERSION);
+
+// checks root exists
+console.log(firebase.SDK_VERSION);
+
+// checks multi-app support exists
+console.log(firebase.functions(firebase.app()).app.name);
+
+// checks default export supports app arg
+console.log(firebase.functions(firebase.app('foo')).app.name);
+
+console.log(firebase.functions.HttpsErrorCode.ABORTED);
+
+firebase
+  .functions()
+  .httpsCallable('foo')(123)
+  .then((result: FirebaseFunctionsTypes.HttpsCallableResult) => {
+    console.log(result.data);
+  })
+  .catch((error: { code: any; details: any }) => {
+    console.log(error.code);
+    console.log(error.details);
+  });
+
+firebase.functions().useFunctionsEmulator('123');
\ No newline at end of file
diff --git a/packages/vertexai/tsconfig.json b/packages/vertexai/tsconfig.json
index f371c6edc9..3ae0a77732 100644
--- a/packages/vertexai/tsconfig.json
+++ b/packages/vertexai/tsconfig.json
@@ -6,9 +6,7 @@
     "esModuleInterop": true,
     "forceConsistentCasingInFileNames": true,
     "jsx": "react-jsx",
-    "lib": [
-      "ESNext"
-    ],
+    "lib": ["ESNext"],
     "module": "ESNext",
     "target": "ESNext",
     "moduleResolution": "Bundler",
@@ -24,7 +22,16 @@
     "strict": true,
     "baseUrl": ".",
     "paths": {
-      "@react-native-firebase/app": ["../app/lib"],
+      "@react-native-firebase/app/lib/common/*": ["../app/dist/typescript/commonjs/lib/common/*"],
+      "@react-native-firebase/app/lib/common": ["../app/dist/typescript/commonjs/lib/common"],
+      "@react-native-firebase/app/lib/internal/web/*": [
+        "../app/dist/typescript/commonjs/lib/internal/web/*"
+      ],
+      "@react-native-firebase/app/lib/internal/*": [
+        "../app/dist/typescript/commonjs/lib/internal/*"
+      ],
+      "@react-native-firebase/app/lib/internal": ["../app/dist/typescript/commonjs/lib/internal"],
+      "@react-native-firebase/app": ["../app/dist/typescript/commonjs/lib"],
       "@react-native-firebase/auth": ["../auth/lib"],
       "@react-native-firebase/app-check": ["../app-check/lib"]
     }
diff --git a/tests/ios/Podfile.lock b/tests/ios/Podfile.lock
index 49986238bd..77b685665b 100644
--- a/tests/ios/Podfile.lock
+++ b/tests/ios/Podfile.lock
@@ -1802,7 +1802,7 @@ PODS:
     - ReactCommon/turbomodule/bridging
     - ReactCommon/turbomodule/core
     - Yoga
-  - RNDeviceInfo (14.1.1):
+  - RNDeviceInfo (15.0.1):
     - React-Core
   - RNFBAnalytics (23.5.0):
     - FirebaseAnalytics/Core (= 12.6.0)
@@ -2298,24 +2298,24 @@ SPEC CHECKSUMS:
   ReactCodegen: 69c7aec61821e1860aaaf959189218ecca40e811
   ReactCommon: ef3e394efce4b78e9214587689c459cf82927368
   RecaptchaInterop: 11e0b637842dfb48308d242afc3f448062325aba
-  RNCAsyncStorage: 6a8127b6987dc9fbce778669b252b14c8355c7ce
-  RNDeviceInfo: bcce8752b5043a623fe3c26789679b473f705d3c
-  RNFBAnalytics: 97c7df49a5316376c95fed222e219b811e7ee3d5
-  RNFBApp: 177e3a5210c6fb436f511cc4413dad0e7c428bfd
-  RNFBAppCheck: d26dabdff94eb45f90fb7c8aa767306c85cdd26d
-  RNFBAppDistribution: 9c78e3cd8087e9c2fb0852e03fb08ace1480e1d7
-  RNFBAuth: 4bcbf1b4b9e1024755dcab122d36a5dafba0e3f3
-  RNFBCrashlytics: 61932725c42d3fed9eb255253b6a833162d6ee08
-  RNFBDatabase: 4954117115f02550bb40ff0736017a60306e7775
-  RNFBFirestore: 2602dab917e06e091b275984722a46c84b88ec48
-  RNFBFunctions: 0bc8036021a91a9fbb4d28cae08c5b1089a307f3
-  RNFBInAppMessaging: 54c3765e20ac9ceaa87afb727e1f18fe4a6a92ac
-  RNFBInstallations: 11a5da460997ba084484222580fe61785b38083a
-  RNFBMessaging: 0835c2f99911197fe95689fea3b4c8725af723f1
-  RNFBML: 2cbc15122658e03c20f088a5c0b99dc116a417a4
-  RNFBPerf: a976bdc076ef268d1d4ccdae69829d4e11bbc172
-  RNFBRemoteConfig: ebca776a11b18ea0070cb3c6c9f29608e397caa3
-  RNFBStorage: fe423da7035c0848bd2a051ff03fb97d5bb1107a
+  RNCAsyncStorage: 481acf401089f312189e100815088ea5dafc583c
+  RNDeviceInfo: 53f9c84e28e854a308d3e548e25ef120b4615531
+  RNFBAnalytics: bd6653e12b1770b4f1b613adfb09f8966bc5156f
+  RNFBApp: d9e2a89c210b1f08fcf3096b15871d8dd896cdae
+  RNFBAppCheck: ceab2b24388cd1fd3a4e23de82e0c7a95bd4e210
+  RNFBAppDistribution: 753dfc0956a35d319eba78828a32ea32ceb53e1d
+  RNFBAuth: eb8385644c405668ef77dc8dfd260283b1bc8b8c
+  RNFBCrashlytics: 2242d1973d2b7d487a0f7cb7a95227f6f90df940
+  RNFBDatabase: 700462a4e6515b8ee80f3a20fbe872c57a9a42ad
+  RNFBFirestore: 4a305c200a7dc57aced0e0ef4ddbede79d758db3
+  RNFBFunctions: afc8ca2a11ff7a6380322ec5e63c58333ead5d79
+  RNFBInAppMessaging: c6a184af904d87614cec5952ff60fdc049200b0b
+  RNFBInstallations: a5ace09d4c76c0e1b929cc4650630bdefd7b3c96
+  RNFBMessaging: 53d0daa2ead6a94d0ae4bdb37bdbebd4ff26fcdd
+  RNFBML: 37c38ac8bff7a8d954b1ac9cc1a3685b9bfa227c
+  RNFBPerf: 859dbab3d443d38a08e28150a0c2ee612332a685
+  RNFBRemoteConfig: abb2609ebc25f2a2bdb3659ce88e4697985492be
+  RNFBStorage: fb85a107606e14f9d9fc919f6f52b9f3e717c79a
   SocketRocket: d4aabe649be1e368d1318fdf28a022d714d65748
   Yoga: 66a9fd80007d5d5fce19d1676ce17b4d5e16e9b1
 
diff --git a/tests/metro.config.js b/tests/metro.config.js
index 23a36c692d..a3de79d720 100644
--- a/tests/metro.config.js
+++ b/tests/metro.config.js
@@ -61,6 +61,24 @@ const config = {
         },
       },
     ),
+    resolveRequest: (context, moduleName, platform) => {
+      // For @react-native-firebase/app subpath imports, redirect lib/* to dist/commonjs/*
+      if (moduleName.startsWith('@react-native-firebase/app/lib/')) {
+        const subpath = moduleName.replace('@react-native-firebase/app/lib/', '');
+        const newModuleName = `@react-native-firebase/app/dist/commonjs/${subpath}`;
+        return context.resolveRequest(context, newModuleName, platform);
+      }
+
+      // For @react-native-firebase/app/common/*, redirect to dist/commonjs/common/*
+      if (moduleName.startsWith('@react-native-firebase/app/common/')) {
+        const subpath = moduleName.replace('@react-native-firebase/app/common/', '');
+        const newModuleName = `@react-native-firebase/app/dist/commonjs/common/${subpath}`;
+        return context.resolveRequest(context, newModuleName, platform);
+      }
+
+      // Let Metro resolve normally
+      return context.resolveRequest(context, moduleName, platform);
+    },
   },
   transformer: {
     unstable_allowRequireContext: true,
diff --git a/tsconfig-jest.json b/tsconfig-jest.json
index 8a42f66917..16b3db65a2 100644
--- a/tsconfig-jest.json
+++ b/tsconfig-jest.json
@@ -4,9 +4,13 @@
     "baseUrl": ".",
     "paths": {
       "@react-native-firebase/app": ["packages/app/lib"],
+      "@react-native-firebase/app/lib/common": ["packages/app/lib/common"],
+      "@react-native-firebase/app/lib/common/*": ["packages/app/lib/common/*"],
+      "@react-native-firebase/app/lib/internal": ["packages/app/lib/internal"],
+      "@react-native-firebase/app/lib/internal/*": ["packages/app/lib/internal/*"],
       "@react-native-firebase/auth": ["packages/auth/lib"],
       "@react-native-firebase/app-check": ["packages/app-check/lib"],
-      "@react-native-firebase/ai": ["packages/ai/lib"],
+      "@react-native-firebase/ai": ["packages/ai/lib"]
     }
   }
 }
diff --git a/tsconfig.json b/tsconfig.json
index 4486da5720..b8201cae57 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,12 +1,12 @@
 {
-  "include": ["packages/**/lib/*.d.ts", "packages/**/type-test.ts"],
+  "include": ["packages/**/lib/**/*.d.ts", "packages/functions/type-test.ts", "packages/app/type-test.ts"],
   "compilerOptions": {
     "noEmit": true,
     "target": "es5",
     "module": "commonjs",
     "declaration": true,
     "importHelpers": true,
-    "jsx": "react",
+    "jsx": "react-native",
     "sourceMap": true,
     "strict": true,
     "noUnusedLocals": true,
@@ -15,10 +15,16 @@
     "noFallthroughCasesInSwitch": true,
     "moduleResolution": "node",
     "skipLibCheck": true,
+    "skipDefaultLibCheck": true,
     "experimentalDecorators": true,
     "emitDecoratorMetadata": true,
     "esModuleInterop": true,
-    "lib": ["es2015", "es2016", "esnext", "dom"]
+    "baseUrl": ".",
+    "lib": ["es2015", "es2016", "esnext", "dom"],
+    "types": ["react-native", "node"],
+    "paths": {
+      "@react-native-firebase/*": ["./packages/*/lib/index.d.ts"]
+    }
   },
-  "exclude": ["node_modules", "**/*.spec.ts"]
+  "exclude": ["node_modules", "**/*.spec.ts", "packages/**/dist"]
 }
diff --git a/yarn.lock b/yarn.lock
index 2becdc9b4f..d30a9bbb95 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -5094,6 +5094,7 @@ __metadata:
     "@react-native-async-storage/async-storage": "npm:^2.2.0"
     expo: "npm:^54.0.27"
     firebase: "npm:12.6.0"
+    react-native-builder-bob: "npm:^0.40.13"
   peerDependencies:
     expo: ">=47.0.0"
     react: "*"
@@ -11119,7 +11120,20 @@ __metadata:
   languageName: node
   linkType: hard
 
-"fast-glob@npm:^3.2.9, fast-glob@npm:^3.3.2, fast-glob@npm:^3.3.3":
+"fast-glob@npm:^3.2.9, fast-glob@npm:^3.3.2":
+  version: 3.3.2
+  resolution: "fast-glob@npm:3.3.2"
+  dependencies:
+    "@nodelib/fs.stat": "npm:^2.0.2"
+    "@nodelib/fs.walk": "npm:^1.2.3"
+    glob-parent: "npm:^5.1.2"
+    merge2: "npm:^1.3.0"
+    micromatch: "npm:^4.0.4"
+  checksum: 10/222512e9315a0efca1276af9adb2127f02105d7288fa746145bf45e2716383fb79eb983c89601a72a399a56b7c18d38ce70457c5466218c5f13fad957cee16df
+  languageName: node
+  linkType: hard
+
+"fast-glob@npm:^3.3.3":
   version: 3.3.3
   resolution: "fast-glob@npm:3.3.3"
   dependencies:
@@ -20265,7 +20279,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"react-native-builder-bob@npm:^0.40.12, react-native-builder-bob@npm:^0.40.16":
+"react-native-builder-bob@npm:^0.40.12, react-native-builder-bob@npm:^0.40.13, react-native-builder-bob@npm:^0.40.16":
   version: 0.40.16
   resolution: "react-native-builder-bob@npm:0.40.16"
   dependencies: