Cloudflare Durable Objects

Status: Production Ready ✅ Last Updated: 2026-01-21 Dependencies: cloudflare-worker-base (recommended) Latest Versions: wrangler@4.58.0, @cloudflare/workers-types@4.20260109.0 Official Docs: https://developers.cloudflare.com/durable-objects/

Recent Updates (2025):

• Oct 2025: WebSocket message size 1 MiB → 32 MiB, Data Studio UI for SQLite DOs (view/edit storage in dashboard)

• Aug 2025: getByName() API shortcut for named DOs

• June 2025: @cloudflare/actors library (beta) - recommended SDK with migrations, alarms, Actor class pattern. Note: Beta stability - see active issues before production use (RPC serialization, vitest integration, memory management)

• May 2025: Python Workers support for Durable Objects

• April 2025: SQLite GA with 10GB storage (beta → GA, 1GB → 10GB), Free tier access

• Feb 2025: PRAGMA optimize support, improved error diagnostics with reference IDs

Quick Start

Scaffold new DO project:

npm create cloudflare@latest my-durable-app -- --template=cloudflare/durable-objects-template --ts

Or add to existing Worker:

// src/counter.ts - Durable Object class import { DurableObject } from 'cloudflare:workers';

export class Counter extends DurableObject { async increment(): Promise<number> { let value = (await this.ctx.storage.get<number>('value')) || 0; await this.ctx.storage.put('value', ++value); return value; } } export default Counter; // CRITICAL: Export required

// wrangler.jsonc - Configuration { "durable_objects": { "bindings": [{ "name": "COUNTER", "class_name": "Counter" }] }, "migrations": [ { "tag": "v1", "new_sqlite_classes": ["Counter"] } // SQLite backend (10GB limit) ] }

// src/index.ts - Worker import { Counter } from './counter'; export { Counter };

export default { async fetch(request: Request, env: { COUNTER: DurableObjectNamespace<Counter> }) { const stub = env.COUNTER.getByName('global-counter'); // Aug 2025: getByName() shortcut return new Response(Count: ${await stub.increment()}); } };

DO Class Essentials

import { DurableObject } from 'cloudflare:workers';

export class MyDO extends DurableObject { constructor(ctx: DurableObjectState, env: Env) { super(ctx, env); // REQUIRED first line

// Load state before requests (optional)
ctx.blockConcurrencyWhile(async () => {
  this.value = await ctx.storage.get('key') || defaultValue;
});

}

// RPC methods (recommended) async myMethod(): Promise<string> { return 'Hello'; }

// HTTP fetch handler (optional) async fetch(request: Request): Promise<Response> { return new Response('OK'); } }

export default MyDO; // CRITICAL: Export required

// Worker must export DO class too import { MyDO } from './my-do'; export { MyDO };

Constructor Rules:

• ✅ Call super(ctx, env) first

• ✅ Keep minimal - heavy work blocks hibernation wake

• ✅ Use ctx.blockConcurrencyWhile() for storage initialization

• ❌ Never setTimeout /setInterval (use alarms)

• ❌ Don't rely on in-memory state with WebSockets (persist to storage)

Storage API

Two backends available:

• SQLite (recommended): 10GB storage, SQL queries, atomic operations, PITR

• KV: 128MB storage, key-value only

Enable SQLite in migrations:

{ "migrations": [{ "tag": "v1", "new_sqlite_classes": ["MyDO"] }] }

SQL API (SQLite backend)

export class MyDO extends DurableObject { sql: SqlStorage;

constructor(ctx: DurableObjectState, env: Env) { super(ctx, env); this.sql = ctx.storage.sql;

this.sql.exec(`
  CREATE TABLE IF NOT EXISTS messages (id INTEGER PRIMARY KEY, text TEXT, created_at INTEGER);
  CREATE INDEX IF NOT EXISTS idx_created ON messages(created_at);
  PRAGMA optimize;  // Feb 2025: Query performance optimization
`);

}

async addMessage(text: string): Promise<number> { const cursor = this.sql.exec('INSERT INTO messages (text, created_at) VALUES (?, ?) RETURNING id', text, Date.now()); return cursor.one<{ id: number }>().id; }

async getMessages(limit = 50): Promise<any[]> { return this.sql.exec('SELECT * FROM messages ORDER BY created_at DESC LIMIT ?', limit).toArray(); } }

SQL Methods:

• sql.exec(query, ...params) → cursor

• cursor.one<T>() → single row (throws if none)

• cursor.one<T>({ allowNone: true }) → row or null

• cursor.toArray<T>() → all rows

• ctx.storage.transactionSync(() => { ... }) → atomic multi-statement

Best Practices:

• ✅ Use ? placeholders for parameterized queries

• ✅ Create indexes on frequently queried columns

• ✅ Use PRAGMA optimize after schema changes

• ✅ Add STRICT keyword to table definitions to enforce type affinity and catch type mismatches early

• ✅ Convert booleans to integers (0/1) - booleans bind as strings "true"/"false" in SQLite backend

Key-Value API (both backends)

// Single operations await this.ctx.storage.put('key', value); const value = await this.ctx.storage.get<T>('key'); await this.ctx.storage.delete('key');

// Batch operations await this.ctx.storage.put({ key1: val1, key2: val2 }); const map = await this.ctx.storage.get(['key1', 'key2']); await this.ctx.storage.delete(['key1', 'key2']);

// List and delete all const map = await this.ctx.storage.list({ prefix: 'user:', limit: 100 }); await this.ctx.storage.deleteAll(); // Atomic on SQLite only

// Transactions await this.ctx.storage.transaction(async (txn) => { await txn.put('key1', val1); await txn.put('key2', val2); });

Storage Limits: SQLite 10GB (April 2025 GA) | KV 128MB

WebSocket Hibernation API

Capabilities:

• Thousands of WebSocket connections per instance

• Hibernate when idle (~10s no activity) to save costs

• Auto wake-up when messages arrive

• Message size limit: 32 MiB (Oct 2025, up from 1 MiB)

How it works:

• Active → handles messages

• Idle → ~10s no activity

• Hibernation → in-memory state cleared, WebSockets stay connected

• Wake → message arrives → constructor runs → handler called

CRITICAL: In-memory state is lost on hibernation. Use serializeAttachment() to persist per-WebSocket metadata.

Hibernation-Safe Pattern

export class ChatRoom extends DurableObject { sessions: Map<WebSocket, { userId: string; username: string }>;

constructor(ctx: DurableObjectState, env: Env) { super(ctx, env); this.sessions = new Map();

// CRITICAL: Restore WebSocket metadata after hibernation
ctx.getWebSockets().forEach((ws) => {
  this.sessions.set(ws, ws.deserializeAttachment());
});

}

async fetch(request: Request): Promise<Response> { const pair = new WebSocketPair(); const [client, server] = Object.values(pair);

const url = new URL(request.url);
const metadata = { userId: url.searchParams.get('userId'), username: url.searchParams.get('username') };

// CRITICAL: Use ctx.acceptWebSocket(), NOT ws.accept()
this.ctx.acceptWebSocket(server);
server.serializeAttachment(metadata);  // Persist across hibernation
this.sessions.set(server, metadata);

return new Response(null, { status: 101, webSocket: client });

}

async webSocketMessage(ws: WebSocket, message: string | ArrayBuffer): Promise<void> { const session = this.sessions.get(ws); // Handle message (max 32 MiB since Oct 2025) }

async webSocketClose(ws: WebSocket, code: number, reason: string, wasClean: boolean): Promise<void> { this.sessions.delete(ws); ws.close(code, 'Closing'); }

async webSocketError(ws: WebSocket, error: any): Promise<void> { this.sessions.delete(ws); } }

Hibernation Rules:

• ✅ ctx.acceptWebSocket(ws)

• enables hibernation

• ✅ ws.serializeAttachment(data)

• persist metadata

• ✅ ctx.getWebSockets().forEach()

• restore in constructor

• ✅ Use alarms instead of setTimeout /setInterval

• ❌ ws.accept()

• standard API, no hibernation

• ❌ setTimeout /setInterval

• prevents hibernation

• ❌ In-progress fetch()

• blocks hibernation

Alarms API

Schedule DO to wake at future time. Use for: batching, cleanup, reminders, periodic tasks.

export class Batcher extends DurableObject { async addItem(item: string): Promise<void> { // Add to buffer const buffer = await this.ctx.storage.get<string[]>('buffer') || []; buffer.push(item); await this.ctx.storage.put('buffer', buffer);

// Schedule alarm if not set
if ((await this.ctx.storage.getAlarm()) === null) {
  await this.ctx.storage.setAlarm(Date.now() + 10000);  // 10 seconds
}

}

async alarm(info: { retryCount: number; isRetry: boolean }): Promise<void> { if (info.retryCount > 3) return; // Give up after 3 retries

const buffer = await this.ctx.storage.get<string[]>('buffer') || [];
await this.processBatch(buffer);
await this.ctx.storage.put('buffer', []);
// Alarm auto-deleted after success

} }

API Methods:

• await ctx.storage.setAlarm(Date.now() + 60000)

• set alarm (overwrites existing)

• await ctx.storage.getAlarm()

• get timestamp or null

• await ctx.storage.deleteAlarm()

• cancel alarm

• async alarm(info)

• handler called when alarm fires

Behavior:

• ✅ At-least-once execution, auto-retries (up to 6x, exponential backoff)

• ✅ Survives hibernation/eviction

• ✅ Auto-deleted after success

• ⚠️ One alarm per DO (new alarm overwrites)

RPC vs HTTP Fetch

RPC (Recommended): Direct method calls, type-safe, simple

// DO class export class Counter extends DurableObject { async increment(): Promise<number> { let value = (await this.ctx.storage.get<number>('count')) || 0; await this.ctx.storage.put('count', ++value); return value; } }

// Worker calls const stub = env.COUNTER.getByName('my-counter'); const count = await stub.increment(); // Type-safe!

HTTP Fetch: Request/response pattern, required for WebSocket upgrades

// DO class export class Counter extends DurableObject { async fetch(request: Request): Promise<Response> { const url = new URL(request.url); if (url.pathname === '/increment') { let value = (await this.ctx.storage.get<number>('count')) || 0; await this.ctx.storage.put('count', ++value); return new Response(JSON.stringify({ count: value })); } return new Response('Not found', { status: 404 }); } }

// Worker calls const stub = env.COUNTER.getByName('my-counter'); const response = await stub.fetch('https://fake-host/increment', { method: 'POST' }); const data = await response.json();

When to use: RPC for new projects (simpler), HTTP Fetch for WebSocket upgrades or complex routing

Getting DO Stubs

Three ways to get IDs:

• idFromName(name)
• Consistent routing (same name = same DO)

const stub = env.CHAT_ROOM.getByName('room-123'); // Aug 2025: Shortcut for idFromName + get // Use for: chat rooms, user sessions, per-tenant logic, singletons

• newUniqueId()
• Random unique ID (must store for reuse)

const id = env.MY_DO.newUniqueId({ jurisdiction: 'eu' }); // Optional: EU compliance const idString = id.toString(); // Save to KV/D1 for later

• idFromString(idString)
• Recreate from saved ID

const id = env.MY_DO.idFromString(await env.KV.get('session:123')); const stub = env.MY_DO.get(id);

Location hints (best-effort):

const stub = env.MY_DO.get(id, { locationHint: 'enam' }); // wnam, enam, sam, weur, eeur, apac, oc, afr, me

Jurisdiction (strict enforcement):

const id = env.MY_DO.newUniqueId({ jurisdiction: 'eu' }); // Options: 'eu', 'fedramp' // Cannot combine with location hints, higher latency outside jurisdiction

Migrations

Required for: create, rename, delete, transfer DO classes

1. Create:

{ "migrations": [{ "tag": "v1", "new_sqlite_classes": ["Counter"] }] } // SQLite 10GB // Or: "new_classes": ["Counter"] // KV 128MB (legacy)

2. Rename:

{ "migrations": [ { "tag": "v1", "new_sqlite_classes": ["OldName"] }, { "tag": "v2", "renamed_classes": [{ "from": "OldName", "to": "NewName" }] } ]}

3. Delete:

{ "migrations": [ { "tag": "v1", "new_sqlite_classes": ["Counter"] }, { "tag": "v2", "deleted_classes": ["Counter"] } // Immediate deletion, cannot undo ]}

4. Transfer:

{ "migrations": [{ "tag": "v1", "transferred_classes": [ { "from": "OldClass", "from_script": "old-worker", "to": "NewClass" } ]}]}

Migration Rules:

• ❌ Atomic (all instances migrate at once, no gradual rollout)

• ❌ Tags are unique and append-only

• ❌ Cannot enable SQLite on existing KV-backed DOs

• ✅ Code changes don't need migrations (only schema changes)

• ✅ Class names globally unique per account

Common Patterns

Rate Limiting:

async checkLimit(userId: string, limit: number, window: number): Promise<boolean> { const requests = (await this.ctx.storage.get<number[]>(rate:${userId})) || []; const valid = requests.filter(t => Date.now() - t < window); if (valid.length >= limit) return false; valid.push(Date.now()); await this.ctx.storage.put(rate:${userId}, valid); return true; }

Session Management with TTL:

async set(key: string, value: any, ttl?: number): Promise<void> { const expiresAt = ttl ? Date.now() + ttl : null; this.sql.exec('INSERT OR REPLACE INTO session (key, value, expires_at) VALUES (?, ?, ?)', key, JSON.stringify(value), expiresAt); }

async alarm(): Promise<void> { this.sql.exec('DELETE FROM session WHERE expires_at < ?', Date.now()); await this.ctx.storage.setAlarm(Date.now() + 3600000); // Hourly cleanup }

Leader Election:

async electLeader(workerId: string): Promise<boolean> { try { this.sql.exec('INSERT INTO leader (id, worker_id, elected_at) VALUES (1, ?, ?)', workerId, Date.now()); return true; } catch { return false; } // Already has leader }

Multi-DO Coordination:

// Coordinator delegates to child DOs const gameRoom = env.GAME_ROOM.getByName(gameId); await gameRoom.initialize(); await this.ctx.storage.put(game:${gameId}, { created: Date.now() });

Critical Rules

Always Do

✅ Export DO class from Worker

export class MyDO extends DurableObject { } export default MyDO; // Required

✅ Call super(ctx, env) in constructor

constructor(ctx: DurableObjectState, env: Env) { super(ctx, env); // Required first line }

✅ Use new_sqlite_classes for new DOs

{ "tag": "v1", "new_sqlite_classes": ["MyDO"] }

✅ Use ctx.acceptWebSocket() for hibernation

this.ctx.acceptWebSocket(server); // Enables hibernation

✅ Persist critical state to storage (not just memory)

await this.ctx.storage.put('important', value);

✅ Use alarms instead of setTimeout/setInterval

await this.ctx.storage.setAlarm(Date.now() + 60000);

✅ Use parameterized SQL queries

this.sql.exec('SELECT * FROM table WHERE id = ?', id);

✅ Minimize constructor work

constructor(ctx, env) { super(ctx, env); // Minimal initialization only ctx.blockConcurrencyWhile(async () => { // Load from storage }); }

Never Do

❌ Create DO without migration

// Missing migrations array = error

❌ Forget to export DO class

class MyDO extends DurableObject { } // Missing: export default MyDO;

❌ Use setTimeout or setInterval

setTimeout(() => {}, 1000); // Prevents hibernation

❌ Rely only on in-memory state with WebSockets

// ❌ WRONG: this.sessions will be lost on hibernation // ✅ CORRECT: Use serializeAttachment()

❌ Deploy migrations gradually

Migrations are atomic - cannot use gradual rollout

❌ Enable SQLite on existing KV-backed DO

// Not supported - must create new DO class instead

❌ Use standard WebSocket API expecting hibernation

ws.accept(); // ❌ No hibernation this.ctx.acceptWebSocket(ws); // ✅ Hibernation enabled

❌ Assume location hints are guaranteed

// Location hints are best-effort only

Known Issues Prevention

This skill prevents 20 documented issues:

Issue #1: Class Not Exported

Error: "binding not found" or "Class X not found"

Source: https://developers.cloudflare.com/durable-objects/get-started/ Why It Happens: DO class not exported from Worker Prevention:

export class MyDO extends DurableObject { } export default MyDO; // ← Required

Issue #2: Missing Migration

Error: "migrations required" or "no migration found for class"

Source: https://developers.cloudflare.com/durable-objects/reference/durable-objects-migrations/ Why It Happens: Created DO class without migration entry Prevention: Always add migration when creating new DO class

{ "migrations": [ { "tag": "v1", "new_sqlite_classes": ["MyDO"] } ] }

Issue #3: Wrong Migration Type (KV vs SQLite)

Error: Schema errors, storage API mismatch Source: https://developers.cloudflare.com/durable-objects/api/sqlite-storage-api/ Why It Happens: Used new_classes instead of new_sqlite_classes

Prevention: Use new_sqlite_classes for SQLite backend (recommended)

Issue #4: Constructor Overhead Blocks Hibernation Wake

Error: Slow hibernation wake-up times Source: https://developers.cloudflare.com/durable-objects/best-practices/access-durable-objects-storage/ Why It Happens: Heavy work in constructor Prevention: Minimize constructor, use blockConcurrencyWhile()

constructor(ctx, env) { super(ctx, env); ctx.blockConcurrencyWhile(async () => { // Load from storage }); }

Issue #5: setTimeout Breaks Hibernation

Error: DO never hibernates, high duration charges Source: https://developers.cloudflare.com/durable-objects/concepts/durable-object-lifecycle/ Why It Happens: setTimeout /setInterval prevents hibernation Prevention: Use alarms API instead

// ❌ WRONG setTimeout(() => {}, 1000);

// ✅ CORRECT await this.ctx.storage.setAlarm(Date.now() + 1000);

Issue #6: In-Memory State Lost on Hibernation

Error: WebSocket metadata lost, state reset unexpectedly Source: https://developers.cloudflare.com/durable-objects/best-practices/websockets/ Why It Happens: Relied on in-memory state that's cleared on hibernation Prevention: Use serializeAttachment() for WebSocket metadata

ws.serializeAttachment({ userId, username });

// Restore in constructor ctx.getWebSockets().forEach(ws => { const metadata = ws.deserializeAttachment(); this.sessions.set(ws, metadata); });

Issue #7: Outgoing WebSocket Cannot Hibernate

Error: High charges despite hibernation API Source: Cloudflare Docs | GitHub Issue #4864 Why It Happens: Durable Objects maintaining persistent connections to external WebSocket services using new WebSocket('url') cannot hibernate and remain pinned in memory indefinitely Use Cases Affected:

• Real-time database subscriptions (Supabase, Firebase)

• Message brokers (Redis Streams, Apache Kafka)

• WebSocket connections to external real-time services

• Inter-service communication Prevention: Only use hibernation for server-side (incoming) WebSockets via ctx.acceptWebSocket() . Outgoing WebSocket connections created with new WebSocket(url) prevent hibernation. Redesign architecture to avoid outgoing WebSocket connections from Durable Objects if hibernation is required.

Issue #8: Global Uniqueness Confusion

Error: Unexpected DO class name conflicts Source: https://developers.cloudflare.com/durable-objects/platform/known-issues/#global-uniqueness Why It Happens: DO class names are globally unique per account Prevention: Understand DO class names are shared across all Workers in account

Issue #9: deleteAll Issues

Error: Storage not fully deleted, billing continues; or internal error in alarm handler Source: KV Storage API | GitHub Issue #2993 Why It Happens:

• KV backend deleteAll() can fail partially (not atomic)

• SQLite: calling deleteAll() in alarm handler causes internal error and retry loop (fixed in runtime) Prevention:

• Use SQLite backend for atomic deleteAll

• In alarm handlers, call deleteAlarm() BEFORE deleteAll() :

async alarm(info: { retryCount: number }): Promise<void> { await this.ctx.storage.deleteAlarm(); // ← Call first await this.ctx.storage.deleteAll(); // Then delete all }

Issue #10: Binding Name Mismatch

Error: Runtime error accessing DO binding Source: https://developers.cloudflare.com/durable-objects/get-started/ Why It Happens: Binding name in wrangler.jsonc doesn't match code Prevention: Ensure consistency

{ "bindings": [{ "name": "MY_DO", "class_name": "MyDO" }] }

env.MY_DO.getByName('instance'); // Must match binding name

Issue #11: State Size Exceeded

Error: "state limit exceeded" or storage errors Source: https://developers.cloudflare.com/durable-objects/platform/pricing/ Why It Happens: Exceeded 1GB (SQLite) or 128MB (KV) limit Prevention: Monitor storage size, implement cleanup with alarms

Issue #12: Migration Not Atomic

Error: Gradual deployment blocked Source: https://developers.cloudflare.com/workers/configuration/versions-and-deployments/gradual-deployments/ Why It Happens: Tried to use gradual rollout with migrations Prevention: Migrations deploy atomically across all instances

Issue #13: Location Hint Ignored

Error: DO created in wrong region Source: https://developers.cloudflare.com/durable-objects/reference/data-location/ Why It Happens: Location hints are best-effort, not guaranteed Prevention: Use jurisdiction for strict requirements

Issue #14: Alarm Retry Failures

Error: Tasks lost after alarm failures Source: https://developers.cloudflare.com/durable-objects/api/alarms/ Why It Happens: Alarm handler throws errors repeatedly Prevention: Implement idempotent alarm handlers

async alarm(info: { retryCount: number }): Promise<void> { if (info.retryCount > 3) { console.error('Giving up after 3 retries'); return; } // Idempotent operation }

Issue #15: Fetch Blocks Hibernation

Error: DO never hibernates despite using hibernation API Source: https://developers.cloudflare.com/durable-objects/concepts/durable-object-lifecycle/ Why It Happens: In-progress fetch() requests prevent hibernation Prevention: Ensure all async I/O completes before idle period

Issue #16: Boolean Values Bind as Strings in SQLite

Error: Boolean columns contain strings "true" /"false" instead of integers 0/1; SQL queries with boolean comparisons fail Source: GitHub Issue #9964 Why It Happens: JavaScript boolean values are serialized as strings in Durable Objects SQLite (inconsistent with D1 behavior) Prevention: Manually convert booleans to integers and use STRICT tables

// Convert booleans to integers this.sql.exec('INSERT INTO test (bool_col) VALUES (?)', value ? 1 : 0);

// Use STRICT tables to catch type mismatches early this.sql.exec( CREATE TABLE IF NOT EXISTS test ( id INTEGER PRIMARY KEY, bool_col INTEGER NOT NULL ) STRICT;);

Issue #17: RPC ReadableStream Cancel Logs False Network Errors

Error: Wrangler dev logs show "Network connection lost" when canceling ReadableStream from RPC, despite correct cancellation Source: GitHub Issue #11071 Why It Happens: Canceling ReadableStream returned from Durable Object via RPC triggers misleading error logs in Wrangler dev (presentation issue, not runtime bug) Prevention: No workaround available. The cancellation works correctly - ignore the false error logs in Wrangler dev. Issue does not appear in production or workerd-only setup.

Issue #18: blockConcurrencyWhile Does Not Block in Local Dev (Fixed)

Error: Constructor's blockConcurrencyWhile doesn't block requests in local dev, causing race conditions hidden during development Source: GitHub Issue #8686 Why It Happens: Bug in older @cloudflare/vite-plugin and wrangler versions Prevention: Upgrade to @cloudflare/vite-plugin v1.3.1+ and wrangler v4.18.0+ where this is fixed

Issue #19: RPC Between Multiple wrangler dev Sessions Not Supported

Error: "Cannot access MyDurableObject#myMethod as Durable Object RPC is not yet supported between multiple wrangler dev sessions"

Source: GitHub Issue #11944 Why It Happens: Accessing a Durable Object over RPC from multiple wrangler dev instances (e.g., separate Workers in monorepo) is not yet supported in local dev Prevention: Use wrangler dev -c config1 -c config2 to run multiple workers in single session, or use HTTP fetch instead of RPC for cross-worker DO communication during local development

Issue #20: state.id.name Undefined in Constructor (vitest Regression)

Error: DurableObjectState.id.name is undefined in constructor when using @cloudflare/vitest-pool-workers 0.8.71 Source: GitHub Issue #11580 Why It Happens: Regression in vitest-pool-workers 0.8.71 (worked in 0.8.38) Prevention: Downgrade to @cloudflare/vitest-pool-workers@0.8.38 or upgrade to later version where this is fixed

Configuration & Types

wrangler.jsonc:

{ "compatibility_date": "2025-11-23", "durable_objects": { "bindings": [{ "name": "COUNTER", "class_name": "Counter" }] }, "migrations": [ { "tag": "v1", "new_sqlite_classes": ["Counter"] }, { "tag": "v2", "renamed_classes": [{ "from": "Counter", "to": "CounterV2" }] } ] }

TypeScript:

import { DurableObject, DurableObjectState, DurableObjectNamespace } from 'cloudflare:workers';

interface Env { MY_DO: DurableObjectNamespace<MyDurableObject>; }

export class MyDurableObject extends DurableObject<Env> { constructor(ctx: DurableObjectState, env: Env) { super(ctx, env); this.sql = ctx.storage.sql; } }

Official Documentation

• Durable Objects: https://developers.cloudflare.com/durable-objects/

• State API (SQL): https://developers.cloudflare.com/durable-objects/api/sqlite-storage-api/

• WebSocket Hibernation: https://developers.cloudflare.com/durable-objects/best-practices/websockets/

• Alarms API: https://developers.cloudflare.com/durable-objects/api/alarms/

• Migrations: https://developers.cloudflare.com/durable-objects/reference/durable-objects-migrations/

• Best Practices: https://developers.cloudflare.com/durable-objects/best-practices/

• Pricing: https://developers.cloudflare.com/durable-objects/platform/pricing/

Questions? Issues?

• Check references/top-errors.md for common problems

• Review templates/ for working examples

• Consult official docs: https://developers.cloudflare.com/durable-objects/

• Verify migrations configuration carefully

Last verified: 2026-01-21 | Skill version: 3.1.0 | Changes: Added 5 new issues (boolean binding, RPC stream cancel, blockConcurrencyWhile local dev, RPC multi-session, vitest regression), expanded Issue #7 (outgoing WebSocket use cases) and Issue #9 (deleteAll alarm interaction), added STRICT tables best practice, updated @cloudflare/actors beta warning