diff --git a/.changeset/purple-symbols-remain.md b/.changeset/purple-symbols-remain.md
new file mode 100644
index 000000000..37fe937f1
--- /dev/null
+++ b/.changeset/purple-symbols-remain.md
@@ -0,0 +1,5 @@
+---
+"@workflow/web": patch
+---
+
+Add PostgreSQL backend support in web UI settings
diff --git a/packages/web/package.json b/packages/web/package.json
index f46a757d2..eec8149d3 100644
--- a/packages/web/package.json
+++ b/packages/web/package.json
@@ -28,6 +28,14 @@
   "dependencies": {
     "next": "15.5.4"
   },
+  "peerDependencies": {
+    "@workflow/world-postgres": "*"
+  },
+  "peerDependenciesMeta": {
+    "@workflow/world-postgres": {
+      "optional": true
+    }
+  },
   "devDependencies": {
     "@biomejs/biome": "catalog:",
     "@radix-ui/react-alert-dialog": "1.1.5",
@@ -51,6 +59,7 @@
     "react": "19.1.0",
     "react-dom": "19.1.0",
     "sonner": "2.0.7",
+    "swr": "2.3.6",
     "tailwind-merge": "2.5.5",
     "tailwindcss": "4",
     "typescript": "catalog:"
diff --git a/packages/web/src/components/settings-sidebar.tsx b/packages/web/src/components/settings-sidebar.tsx
index f5affa3ba..3b3682e53 100644
--- a/packages/web/src/components/settings-sidebar.tsx
+++ b/packages/web/src/components/settings-sidebar.tsx
@@ -1,7 +1,7 @@
 /** biome-ignore-all lint/correctness/useUniqueElementIds: <not relevant> */
 'use client';
 
-import { AlertCircle, Settings, X } from 'lucide-react';
+import { AlertCircle, AlertTriangle, Settings, X } from 'lucide-react';
 import { useEffect, useState } from 'react';
 import { Alert, AlertDescription, AlertTitle } from '@/components/ui/alert';
 import { Button } from '@/components/ui/button';
@@ -20,6 +20,7 @@ import {
   validateWorldConfig,
   type WorldConfig,
 } from '@/lib/config-world';
+import { useWorldsAvailability } from '@/lib/hooks';
 
 export function SettingsSidebar() {
   const config = useQueryParamConfig();
@@ -30,8 +31,12 @@ export function SettingsSidebar() {
   const [errors, setErrors] = useState<ValidationError[]>([]);
   const [isValidating, setIsValidating] = useState(false);
 
+  const { data: worldsAvailability = [], isLoading: isLoadingWorlds } =
+    useWorldsAvailability();
+
   const backend = localConfig.backend || 'embedded';
   const isEmbedded = backend === 'embedded';
+  const isPostgres = backend === 'postgres';
 
   // Update local config when query params change
   useEffect(() => {
@@ -121,10 +126,48 @@ export function SettingsSidebar() {
                       <SelectValue placeholder="Select backend" />
                     </SelectTrigger>
                     <SelectContent>
-                      <SelectItem value="embedded">Embedded</SelectItem>
-                      <SelectItem value="vercel">Vercel</SelectItem>
+                      {isLoadingWorlds ? (
+                        <SelectItem value="loading" disabled>
+                          Loading worlds...
+                        </SelectItem>
+                      ) : worldsAvailability.length > 0 ? (
+                        worldsAvailability.map((world) => (
+                          <SelectItem key={world.id} value={world.id}>
+                            {world.displayName}
+                          </SelectItem>
+                        ))
+                      ) : (
+                        <>
+                          <SelectItem value="embedded">Embedded</SelectItem>
+                          <SelectItem value="vercel">Vercel</SelectItem>
+                          <SelectItem value="postgres">PostgreSQL</SelectItem>
+                        </>
+                      )}
                     </SelectContent>
                   </Select>
+                  {/* Show warning if selected world is not installed */}
+                  {(() => {
+                    const selectedWorld = worldsAvailability.find(
+                      (w) => w.id === backend
+                    );
+                    if (selectedWorld && !selectedWorld.isInstalled) {
+                      return (
+                        <div className="flex items-start gap-2 p-2 rounded-md bg-amber-500/10 border border-amber-500/20 text-amber-600 dark:text-amber-400">
+                          <AlertTriangle className="h-4 w-4 mt-0.5 shrink-0" />
+                          <div className="text-xs">
+                            <p className="font-medium">Package not installed</p>
+                            <p className="mt-1 text-muted-foreground">
+                              Run:{' '}
+                              <code className="bg-muted px-1 py-0.5 rounded">
+                                {selectedWorld.installCommand}
+                              </code>
+                            </p>
+                          </div>
+                        </div>
+                      );
+                    }
+                    return null;
+                  })()}
                 </div>
 
                 {isEmbedded && (
@@ -175,7 +218,33 @@ export function SettingsSidebar() {
                   </>
                 )}
 
-                {!isEmbedded && (
+                {isPostgres && (
+                  <>
+                    <div className="space-y-2">
+                      <Label htmlFor="postgresUrl">Connection URL</Label>
+                      <Input
+                        id="postgresUrl"
+                        value={localConfig.postgresUrl || ''}
+                        onChange={(e) =>
+                          handleInputChange('postgresUrl', e.target.value)
+                        }
+                        placeholder="postgres://user:pass@host:5432/db"
+                        className={
+                          getFieldError('postgresUrl')
+                            ? 'border-destructive'
+                            : ''
+                        }
+                      />
+                      {getFieldError('postgresUrl') && (
+                        <p className="text-sm text-destructive">
+                          {getFieldError('postgresUrl')}
+                        </p>
+                      )}
+                    </div>
+                  </>
+                )}
+
+                {!isEmbedded && !isPostgres && (
                   <>
                     <div className="space-y-2">
                       <Label htmlFor="env">Environment</Label>
@@ -250,7 +319,13 @@ export function SettingsSidebar() {
                 <div className="flex flex-col gap-2 pt-4">
                   <Button
                     onClick={handleValidateAndApply}
-                    disabled={isValidating || !hasChanges}
+                    disabled={
+                      isValidating ||
+                      !hasChanges ||
+                      worldsAvailability.some(
+                        (w) => w.id === backend && !w.isInstalled
+                      )
+                    }
                     className="w-full"
                   >
                     {isValidating ? 'Validating...' : 'Apply Configuration'}
diff --git a/packages/web/src/lib/config-world.ts b/packages/web/src/lib/config-world.ts
index 25a568c23..897a5adcc 100644
--- a/packages/web/src/lib/config-world.ts
+++ b/packages/web/src/lib/config-world.ts
@@ -1,7 +1,11 @@
 'use server';
 
+import { createRequire } from 'node:module';
 import { existsSync } from 'node:fs';
-import { resolve } from 'node:path';
+import { join, resolve } from 'node:path';
+import { KNOWN_WORLDS, type KnownWorld } from './known-worlds';
+
+const require = createRequire(join(process.cwd(), 'index.js'));
 
 export interface WorldConfig {
   backend?: string;
@@ -11,6 +15,8 @@ export interface WorldConfig {
   team?: string;
   port?: string;
   dataDir?: string;
+  // Postgres fields
+  postgresUrl?: string;
 }
 
 export interface ValidationError {
@@ -18,6 +24,48 @@ export interface ValidationError {
   message: string;
 }
 
+export interface WorldAvailability {
+  id: string;
+  displayName: string;
+  packageName: string | null;
+  description: string;
+  isBuiltIn: boolean;
+  isInstalled: boolean;
+  installCommand?: string;
+}
+
+/**
+ * Check which world packages are installed.
+ *
+ * Built-in worlds (embedded, vercel) are always available.
+ * Third-party worlds are checked by attempting to resolve their package.
+ */
+export async function checkWorldsAvailability(): Promise<WorldAvailability[]> {
+  return KNOWN_WORLDS.map((world: KnownWorld) => {
+    const availability: WorldAvailability = {
+      id: world.id,
+      displayName: world.displayName,
+      packageName: world.packageName,
+      description: world.description,
+      isBuiltIn: world.isBuiltIn,
+      isInstalled: world.isBuiltIn, // Built-in worlds are always installed
+    };
+
+    // For non-built-in worlds, try to resolve the package
+    if (!world.isBuiltIn && world.packageName) {
+      try {
+        require.resolve(world.packageName);
+        availability.isInstalled = true;
+      } catch {
+        availability.isInstalled = false;
+        availability.installCommand = `npm install ${world.packageName}`;
+      }
+    }
+
+    return availability;
+  });
+}
+
 // Validate configuration and return errors if any
 export async function validateWorldConfig(
   config: WorldConfig
@@ -49,5 +97,24 @@ export async function validateWorldConfig(
     }
   }
 
+  if (backend === 'postgres') {
+    // Validate postgres connection string
+    if (!config.postgresUrl) {
+      errors.push({
+        field: 'postgresUrl',
+        message: 'PostgreSQL connection string is required',
+      });
+    } else if (
+      !config.postgresUrl.startsWith('postgres://') &&
+      !config.postgresUrl.startsWith('postgresql://')
+    ) {
+      errors.push({
+        field: 'postgresUrl',
+        message:
+          'Invalid PostgreSQL connection string format (must start with postgres:// or postgresql://)',
+      });
+    }
+  }
+
   return errors;
 }
diff --git a/packages/web/src/lib/config.ts b/packages/web/src/lib/config.ts
index 6d01d59a5..fc3e1f218 100644
--- a/packages/web/src/lib/config.ts
+++ b/packages/web/src/lib/config.ts
@@ -13,6 +13,15 @@ const DEFAULT_CONFIG: WorldConfig = {
   env: 'production',
 };
 
+export const resolveTargetWorld = (backend?: string) => {
+  switch (backend) {
+    case 'postgres':
+      return '@workflow/world-postgres';
+    default:
+      return backend;
+  }
+};
+
 // Config query param keys
 const CONFIG_PARAM_KEYS = [
   'backend',
@@ -22,6 +31,7 @@ const CONFIG_PARAM_KEYS = [
   'team',
   'port',
   'dataDir',
+  'postgresUrl',
 ] as const;
 
 /**
@@ -133,12 +143,14 @@ export function buildUrlWithConfig(
 
 export const worldConfigToEnvMap = (config: WorldConfig): EnvMap => {
   return {
-    WORKFLOW_TARGET_WORLD: config.backend,
+    WORKFLOW_TARGET_WORLD: resolveTargetWorld(config.backend),
     WORKFLOW_VERCEL_ENV: config.env,
     WORKFLOW_VERCEL_AUTH_TOKEN: config.authToken,
     WORKFLOW_VERCEL_PROJECT: config.project,
     WORKFLOW_VERCEL_TEAM: config.team,
     PORT: config.port,
     WORKFLOW_EMBEDDED_DATA_DIR: config.dataDir,
+    // Postgres env vars
+    WORKFLOW_POSTGRES_URL: config.postgresUrl,
   };
 };
diff --git a/packages/web/src/lib/hooks.ts b/packages/web/src/lib/hooks.ts
new file mode 100644
index 000000000..7f3ff5c43
--- /dev/null
+++ b/packages/web/src/lib/hooks.ts
@@ -0,0 +1,10 @@
+'use client';
+
+import useSWR from 'swr';
+import { checkWorldsAvailability } from './config-world';
+
+export function useWorldsAvailability() {
+  return useSWR('worlds-availability', checkWorldsAvailability, {
+    revalidateOnFocus: false,
+  });
+}
diff --git a/packages/web/src/lib/known-worlds.ts b/packages/web/src/lib/known-worlds.ts
new file mode 100644
index 000000000..d26a61ebd
--- /dev/null
+++ b/packages/web/src/lib/known-worlds.ts
@@ -0,0 +1,50 @@
+/**
+ * Registry of known world packages that the UI can work with.
+ *
+ * This file defines the metadata for worlds that can be selected in the
+ * configuration UI. Worlds are dynamically loaded at runtime - they don't
+ * need to be direct dependencies of the web package.
+ */
+
+export interface KnownWorld {
+  /** Unique identifier used in the UI and query params */
+  id: string;
+  /** Human-readable display name */
+  displayName: string;
+  /** npm package name (or null for built-in worlds) */
+  packageName: string | null;
+  /** Short description of the world */
+  description: string;
+  /** Whether this world is bundled with @workflow/core */
+  isBuiltIn: boolean;
+}
+
+/**
+ * List of known worlds that can be configured in the UI.
+ *
+ * Built-in worlds (embedded, vercel) are always available as they're bundled
+ * with @workflow/core. Third-party worlds need to be installed separately.
+ */
+export const KNOWN_WORLDS: KnownWorld[] = [
+  {
+    id: 'embedded',
+    displayName: 'Embedded',
+    packageName: null,
+    description: 'Local file-based storage, ideal for development',
+    isBuiltIn: true,
+  },
+  {
+    id: 'vercel',
+    displayName: 'Vercel',
+    packageName: null,
+    description: 'Vercel-managed storage and queue',
+    isBuiltIn: true,
+  },
+  {
+    id: 'postgres',
+    displayName: 'PostgreSQL',
+    packageName: '@workflow/world-postgres',
+    description: 'PostgreSQL-based storage with pg-boss queue',
+    isBuiltIn: false,
+  },
+];
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 86986b5e8..bbf7110d8 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -760,6 +760,9 @@ importers:
 
   packages/web:
     dependencies:
+      '@workflow/world-postgres':
+        specifier: '*'
+        version: 4.1.0-beta.15(@opentelemetry/api@1.9.0)(better-sqlite3@11.10.0)(pg@8.16.3)
       next:
         specifier: 15.5.4
         version: 15.5.4(@opentelemetry/api@1.9.0)(react-dom@19.1.0(react@19.1.0))(react@19.1.0)
@@ -830,6 +833,9 @@ importers:
       sonner:
         specifier: 2.0.7
         version: 2.0.7(react-dom@19.1.0(react@19.1.0))(react@19.1.0)
+      swr:
+        specifier: 2.3.6
+        version: 2.3.6(react@19.1.0)
       tailwind-merge:
         specifier: 2.5.5
         version: 2.5.5
@@ -6442,6 +6448,29 @@ packages:
     resolution: {integrity: sha512-ueFCcIPaMgtuYDS9u0qlUoEvj6GiSsKrwnOLPp9SshqjtcRaR1IEHRjoReq3sXNydsF5i0ZnmuYgXq9dV53t0g==}
     engines: {node: '>=18.0.0'}
 
+  '@workflow/errors@4.0.1-beta.6':
+    resolution: {integrity: sha512-D6MZQofkjRo9RAkgh44LNzzKUD6dhRJ4B5IuOCMoJuIBE5PxqcL5oCuIwFt532FLmhNAP1/pjqe/nGeQNuwn+w==}
+
+  '@workflow/utils@4.0.1-beta.4':
+    resolution: {integrity: sha512-/zeoQ9uEwDt+1/IcgUW/fAUEbYgNCKbXD19eIuh+3XULz7p9NJ1ApFLFL5p9gUnaeNcIuuMjWJ1QOOp+RHnc+A==}
+
+  '@workflow/world-local@4.0.1-beta.13':
+    resolution: {integrity: sha512-VIGBMTJlBd4l/ygs1m6FuSd5UDs1lXRQKve5m2HNVBD8MWUHgvR/MoYc19hf3qXBGV7+RhmuDhqBiso2akUv3A==}
+    peerDependencies:
+      '@opentelemetry/api': '1'
+    peerDependenciesMeta:
+      '@opentelemetry/api':
+        optional: true
+
+  '@workflow/world-postgres@4.1.0-beta.15':
+    resolution: {integrity: sha512-gk8ygvpAXGJD0J6s1ME+lj1Wsme+tTYa0zfdjaYgGw7meuGdSJM4JQVfBWWQYe86xDjB/lt4EDinT9auBesLEg==}
+    hasBin: true
+
+  '@workflow/world@4.0.1-beta.7':
+    resolution: {integrity: sha512-kPL5Acu+Wr0My2c76+YADCfSu7QVffHyn4saSTHvr3rQMa8OWmE6trhV5apglmHMpoTkoFQDVqa3rrSRZ/NeOQ==}
+    peerDependencies:
+      zod: 4.1.11
+
   abbrev@3.0.1:
     resolution: {integrity: sha512-AO2ac6pjRB3SJmGJo+v5/aK6Omggp6fsLrs6wN9bd35ulu4cCwaAU9+7ZhXjeqHVkaHThLuzH0nZr0YpCDhygg==}
     engines: {node: ^18.17.0 || >=20.5.0}
@@ -18024,6 +18053,76 @@ snapshots:
       '@whatwg-node/promise-helpers': 1.3.2
       tslib: 2.8.1
 
+  '@workflow/errors@4.0.1-beta.6':
+    dependencies:
+      '@workflow/utils': 4.0.1-beta.4
+      ms: 2.1.3
+
+  '@workflow/utils@4.0.1-beta.4':
+    dependencies:
+      execa: 9.6.0
+      ms: 2.1.3
+
+  '@workflow/world-local@4.0.1-beta.13(@opentelemetry/api@1.9.0)':
+    dependencies:
+      '@vercel/queue': 0.0.0-alpha.29
+      '@workflow/utils': 4.0.1-beta.4
+      '@workflow/world': 4.0.1-beta.7(zod@4.1.11)
+      async-sema: 3.1.1
+      ulid: 3.0.1
+      undici: 6.19.0
+      zod: 4.1.11
+    optionalDependencies:
+      '@opentelemetry/api': 1.9.0
+
+  '@workflow/world-postgres@4.1.0-beta.15(@opentelemetry/api@1.9.0)(better-sqlite3@11.10.0)(pg@8.16.3)':
+    dependencies:
+      '@vercel/queue': 0.0.0-alpha.29
+      '@workflow/errors': 4.0.1-beta.6
+      '@workflow/world': 4.0.1-beta.7(zod@4.1.11)
+      '@workflow/world-local': 4.0.1-beta.13(@opentelemetry/api@1.9.0)
+      cbor-x: 1.6.0
+      dotenv: 16.4.5
+      drizzle-orm: 0.44.7(@opentelemetry/api@1.9.0)(better-sqlite3@11.10.0)(pg@8.16.3)(postgres@3.4.7)
+      pg-boss: 11.0.7
+      postgres: 3.4.7
+      ulid: 3.0.1
+      zod: 4.1.11
+    transitivePeerDependencies:
+      - '@aws-sdk/client-rds-data'
+      - '@cloudflare/workers-types'
+      - '@electric-sql/pglite'
+      - '@libsql/client'
+      - '@libsql/client-wasm'
+      - '@neondatabase/serverless'
+      - '@op-engineering/op-sqlite'
+      - '@opentelemetry/api'
+      - '@planetscale/database'
+      - '@prisma/client'
+      - '@tidbcloud/serverless'
+      - '@types/better-sqlite3'
+      - '@types/pg'
+      - '@types/sql.js'
+      - '@upstash/redis'
+      - '@vercel/postgres'
+      - '@xata.io/client'
+      - better-sqlite3
+      - bun-types
+      - expo-sqlite
+      - gel
+      - knex
+      - kysely
+      - mysql2
+      - pg
+      - pg-native
+      - prisma
+      - sql.js
+      - sqlite3
+
+  '@workflow/world@4.0.1-beta.7(zod@4.1.11)':
+    dependencies:
+      zod: 4.1.11
+
   abbrev@3.0.1: {}
 
   abort-controller@3.0.0: