bun.sh/docs/runtime/bun-apis.md

Bun implements a set of native APIs on the Bun global object and through a number of built-in modules. These APIs are heavily optimized and represent the canonical "Bun-native" way to implement some common functionality.

Bun strives to implement standard Web APIs wherever possible. Bun introduces new APIs primarily for server-side tasks where no standard exists, such as file I/O and starting an HTTP server. In these cases, Bun's approach still builds atop standard APIs like Blob, URL, and Request.

Bun.serve({
  fetch(req: Request) {
    return new Response("Success!");
  },
});

Click the link in the right column to jump to the associated documentation.

{% table %}

• Topic
• APIs

---

• HTTP Server
• Bun.serve

---

• Shell
• $

---

• Bundler
• Bun.build

---

• File I/O
• Bun.file, Bun.write, Bun.stdin, Bun.stdout, Bun.stderr

---

• Child Processes
• Bun.spawn, Bun.spawnSync

---

• TCP Sockets
• Bun.listen, Bun.connect

---

• UDP Sockets
• Bun.udpSocket

---

• WebSockets
• new WebSocket() (client), Bun.serve (server)

---

• Transpiler
• Bun.Transpiler

---

• Routing
• Bun.FileSystemRouter

---

• Streaming HTML
• HTMLRewriter

---

• Hashing
• Bun.password, Bun.hash, Bun.CryptoHasher, Bun.sha

---

• SQLite
• bun:sqlite

---

• PostgreSQL Client
• Bun.SQL, Bun.sql

---

• Redis (Valkey) Client
• Bun.RedisClient, Bun.redis

---

• FFI (Foreign Function Interface)
• bun:ffi

---

• DNS
• Bun.dns.lookup, Bun.dns.prefetch, Bun.dns.getCacheStats

---

• Testing
• bun:test

---

• Workers
• new Worker()

---

• Module Loaders
• Bun.plugin

---

• Glob
• Bun.Glob

---

• Cookies
• Bun.Cookie, Bun.CookieMap

---

• Node-API
• Node-API

---

• import.meta
• import.meta

---

• Utilities
• Bun.version, Bun.revision, Bun.env, Bun.main

---

• Sleep & Timing
• Bun.sleep(), Bun.sleepSync(), Bun.nanoseconds()

---

• Random & UUID
• Bun.randomUUIDv7()

---

• System & Environment
• Bun.which()

---

• Comparison & Inspection
• Bun.peek(), Bun.deepEquals(), Bun.deepMatch, Bun.inspect()

---

• String & Text Processing
• Bun.escapeHTML(), Bun.stringWidth(), Bun.indexOfLine

---

• URL & Path Utilities
• Bun.fileURLToPath(), Bun.pathToFileURL()

---

• Compression
• Bun.gzipSync(), Bun.gunzipSync(), Bun.deflateSync(), Bun.inflateSync(), Bun.zstdCompressSync(), Bun.zstdDecompressSync(), Bun.zstdCompress(), Bun.zstdDecompress()

---

• Stream Processing
• Bun.readableStreamTo*(), Bun.readableStreamToBytes(), Bun.readableStreamToBlob(), Bun.readableStreamToFormData(), Bun.readableStreamToJSON(), Bun.readableStreamToArray()

---

• Memory & Buffer Management
• Bun.ArrayBufferSink, Bun.allocUnsafe, Bun.concatArrayBuffers

---

• Module Resolution
• Bun.resolveSync()

---

• Parsing & Formatting
• Bun.semver, Bun.TOML.parse, Bun.color

---

• Low-level / Internals
• Bun.mmap, Bun.gc, Bun.generateHeapSnapshot, bun:jsc

---

{% /table %}