durable-objects

Build stateful chat rooms or multiplayer sessions with Cloudflare Workers by assigning one Durable Object per logical unit, encapsulating coordination and storage using RPC methods, WebSockets, and SQLite-backed persistence.

A Durable Object is a stateful, per-entity coordination primitive at the edge. You need it for scalable, consistent per-entity logic across workers, such as multi-tenant coordination, live collaborative apps, or turn-based systems.

Persist state in a Durable Object using integrated SQLite storage with migrations. Define storage operations within your DO class, connect it to wrangler, and apply storage-first persistence practices to maintain consistent per-entity state.

Cloudflare Workers Durable Objects support WebSocket connections and RPC-style methods to manage per-entity state and real-time communication for live collaborative apps and multiplayer sessions.

Test Durable Objects logic with Vitest by enforcing best practices for deterministic routing and testability. Create a DO class, expose deterministic RPC methods, and validate per-entity coordination and storage behavior.

Limitations of Durable Objects for per-user coordination include strict per-entity routing and storage constraints. They enforce deterministic routing and storage-first persistence, requiring careful design for scalable, consistent state logic across workers.