API REFERENCE
The right API, in the right place.
Bun puts the runtime, HTTP server, SQL, testing, and bundler in one toolkit. Browse the core APIs by topic — every section links to full docs and runnable examples.
Runtime APIs
Bun.serve, file I/O, SQLite, S3, hashing, environment variables, and the Node.js compatibility layer.
HTTP & networking
A native HTTP server, routing, WebSockets, TLS, TCP, UDP, and DNS.
Data & storage
Built-in SQLite, a Postgres client, Redis, S3, streams, and binary data.
Testing
A Jest-compatible test runner with snapshots, DOM, mocks, coverage, and watch mode.