Bun v1.3 is here! Redis, MySQL, SQLite, better Node compatibility →

Bun is a fast JavaScript
all-in-one toolkit|

Bun is a fast, incrementally adoptable all-in-one JavaScript, TypeScript & JSX toolkit. Use individual tools like bun test or bun install in Node.js projects, or adopt the complete stack with a fast JavaScript runtime, bundler, test runner, and package manager built in. Bun aims for 100% Node.js compatibility.

Install Bun v1.3

View install script

curl -fsSL https://bun.sh/install | bash

USED BY

Four tools, one toolkit

Use them together as an all-in-one toolkit, or adopt them incrementally. bun test works in Node.js projects. bun install can be used as the fastest npm client. Each tool stands on its own.

JavaScript Runtime

Starts 3x faster than Node.js

A fast JavaScript runtime designed as a drop-in replacement for Node.js

$ bun ./index.ts

Package Manager

30x faster

Install packages up to 30x faster than npm with a global cache and workspaces

$ bun install

Test Runner

Replaces Jest & Vitest

Jest-compatible test runner with built-in code coverage and watch mode

$ bun test

Bundler

Replaces Vite and esbuild

Bundle TypeScript, JSX, React & CSS for both browsers and servers

$ bun build ./app.tsx

✓TypeScript & JSX built-in (no config)
✓CSS imports & bundling
✓React support out of the box
✓Build for the browser, Bun, and Node.js
✓Single-file executables
✓.html, .css, .ts, .tsx, .jsx & more

Who uses Bun?

Claude Code uses Bun

Bun's single file executables & fast start times are great for CLIs.

Learn about single file executables

Railway Functions powered by Bun

Bun's all-in-one toolkit makes Railway's serverless functions fast and easy to use.

Deploy on Railway

Midjourney uses Bun

Bun's built-in WebSocket server helps Midjourney publish image generation notifications at scale.

Learn about Bun's WebSocket server

What's different about Bun?

Bun provides extensive builtin APIs and tooling

Builtin Core Features Essential runtime capabilities	Bun	Node	Deno
Node.js compatibility Aiming to be a drop-in replacement for Node.js apps
Web Standard APIs Support for web standard APIs like `fetch`, `URL`, `EventTarget`, `Headers`, etc.	Powered by WebCore (from WebKit/Safari)
Native Addons Call C-compatible native code from JavaScript	Bun.ffi, NAPI, partial V8 C++ API
TypeScript First-class support, including `"paths"` `enum` `namespace`
JSX First-class support without configuration
Module loader plugins Plugin API for importing/requiring custom file types	`Bun.plugin` works in browsers & Bun	3 different loader APIs. Server-side only
Builtin APIs Built-in performance and native APIs designed for production	Bun	Node	Deno
PostgreSQL, MySQL, and SQLite drivers Connect to any SQL database with one fast, unified API	Fastest available, with query pipelining
S3 Cloud Storage driver Upload and download from S3-compatible storage, built-in	Fastest available
Redis client Redis client built into Bun with Pub/Sub support
WebSocket server (including pub/sub) WebSocket server built into `Bun.serve()` with backpressure handling	`Bun.serve()`
HTTP server Lightning-fast HTTP server built into Bun	Bun.serve()
HTTP router Route HTTP requests with dynamic paths and wildcards, built into `Bun.serve()`	Bun.serve({routes: {'/api/:path': (req) => { ... }}}})
Single-file executables Compile your app to a standalone executable that runs anywhere	bun build --compile with cross-compilation & code signing	No native addons, embedded files, cross-compilation or bytecode. Multi-step process.	No native addons, no cross-compilation
YAML YAML is a first-class citizen in Bun, just like JSON	Bun.YAML & import from .yaml files
Cookies API Parse and set cookies with zero overhead using a Map-like API	request.cookies Map-like API
Encrypted Secrets Storage Store secrets securely using your OS's native keychain	Bun.secrets (Keychain/libsecret/Windows Credential Manager)
Builtin Tooling Built-in developer tooling	Bun	Node	Deno
npm package management Install, manage, and publish npm-compatible dependencies	With catalogs, isolated installs, bun audit, bun why		Limited features
Bundler Build production-ready code for frontend & backend	Bun.build
Cross-platform $ shell API Native bash-like shell for cross-platform shell scripting	`Bun.$`		Requires 'dax'
Jest-compatible test runner Testing library compatible with the most popular testing framework	bun test with VS Code integration & concurrent execution
Hot reloading (server) Reload your backend without disconnecting connections, preserving state	bun --hot
Monorepo support Install workspaces packages and run commands across workspaces	bun run --filter=package-glob ...
Frontend Development Server Run modern frontend apps with a fully-featured dev server	bun ./index.html
Formatter & Linter Built-in formatter and linter
Builtin Utilities APIs that make your life easier as a developer	Bun	Node	Deno
Password & Hashing APIs `bcrypt`, `argon2`, and non-cryptographic hash functions	`Bun.password` & `Bun.hash`
String Width API Calculate the width of a string as displayed in the terminal	Bun.stringWidth
Glob API Glob patterns for file matching	Bun.Glob	fs.promises.glob
Semver API Compare and sort semver strings	Bun.semver
CSS color conversion API Convert between CSS color formats	Bun.color
CSRF API Generate and verify CSRF tokens	Bun.CSRF

Everything you need to build & ship

Production-ready APIs and tools, built into Bun

HTTP & WebSockets

Databases

File System

Testing

Build & Deploy

TypeScript & DX

Security

System Integration

Utilities

$ bun run

Bun is a JavaScript runtime.

Bun is a new JavaScript runtime built from scratch to serve the modern JavaScript ecosystem. It has three major design goals:

Speed. Bun starts fast and runs fast. It extends JavaScriptCore, the performance-minded JS engine built for Safari. Fast start times mean fast apps and fast APIs.
Elegant APIs. Bun provides a minimal set of highly-optimized APIs for performing common tasks, like starting an HTTP server and writing files.
Cohesive DX. Bun is a complete toolkit for building JavaScript apps, including a package manager, test runner, and bundler.

Bun is designed as a drop-in replacement for Node.js. It natively implements thousands of Node.js and Web APIs, including fs, path, Buffer and more.

The goal of Bun is to run most of the world's server-side JavaScript and provide tools to improve performance, reduce complexity, and multiply developer productivity.

Bun works with Next.js

Lee Robinson

VP of Developer Experience at Cursor (Anysphere)

app/blog/[slug]/page.tsx

import { s3, $, sql } from "bun";

export default async function BlogPage({ params }) {

const [post] = await sql`

SELECT title, image_key, content

FROM posts

WHERE slug = ${params.slug}

const imgUrl = s3.file(post.image_key).presign({•••});

const wordCount = await $`echo ${post.content} | wc -w`;

return (

<div>

<h1>{post.title}</h1>

<p>Word count: {wordCount}</p>

</div>

);

}

Full speed full-stack

Fast frontend apps with Bun's built-in high performance development server and production bundler. You've never seen hot-reloading this fast!

Develop and ship frontend apps

Bun's built-in bundler and dev server make frontend development fast and simple. Develop with instant hot reload, then ship optimized production builds—all with zero configuration.

$ bun init --react

Start a dev server

Run bun ./index.html to start a dev server. TypeScript, JSX, React, and CSS imports work out of the box.

Hot Module Replacement

Built-in HMR preserves application state during development. Changes appear instantly—no manual refresh needed.

Build for production

Build optimized bundles with bun build ./index.html --production. Tree-shaking, minification, and code splitting work out of the box.

Learn more about frontend with Bun →

$ bun install

Bun is an npm-compatible package manager.

Bun

pnpm

17x slower

npm

29x slower

Yarn

33x slower

Installing dependencies from cache for a Remix app.
View benchmark

Replace yarn with bun install to get 30x faster package installs.

$ bun test

Bun is a test runner that makes the rest look like test walkers.

Bun

Vitest

5x slower

Jest+SWC

8x slower

Jest+tsjest

18x slower

Jest+Babel

20x slower

Replace jest with bun test to run your tests 10-30x faster.

The APIs you need. Baked in.

Start an HTTP server

Start a WebSocket server

Read and write files

Hash a password

Frontend dev server

Write a test

Query PostgreSQL

Use Redis

Import YAML

Set cookies

Run a shell script

Call a C function

index.tsx
import { sql, serve } from "bun";

const server = serve({
  port: 3000,
  routes: {
    "/": () => new Response("Welcome to Bun!"),
    "/api/users": async (req) => {
      const users = await sql`SELECT * FROM users LIMIT 10`;
      return Response.json({ users });
    },
  },
});

console.log(`Listening on localhost:${server.port}`);

index.tsx
const server = Bun.serve<{ authToken: string; }>({
  fetch(req, server) {
    // use a library to parse cookies
    const cookies = parseCookies(req.headers.get("Cookie"));
    server.upgrade(req, {
      data: { authToken: cookies['X-Token'] },
    });
  },
  websocket: {
    // handler called when a message is received
    async message(ws, message) {
      console.log(`Received: ${message}`);
      const user = getUserFromToken(ws.data.authToken);
      await db.Message.insert({
        message: String(message),
        userId: user.id,
      });
    },
  },
});

console.log(`Listening on localhost:${server.port}`);

index.tsx
const file = Bun.file(import.meta.dir + '/package.json'); // BunFile

const pkg = await file.json(); // BunFile extends Blob
pkg.name = 'my-package';
pkg.version = '1.0.0';

await Bun.write(file, JSON.stringify(pkg, null, 2));

index.tsx
const password = "super-secure-pa$$word";

const hash = await Bun.password.hash(password);
// => $argon2id$v=19$m=65536,t=2,p=1$tFq+9AVr1bfPxQdh...

const isMatch = await Bun.password.verify(password, hash);
// => true

server.ts
// Run 'bun init --react' to get started
import { serve } from "bun";
import reactApp from "./index.html";

serve({
  port: 3000,
  routes: {
    "/": reactApp,
    "/api/hello": () => Response.json({ message: "Hello!" }),
  },
  development: {
    console: true, // Stream browser logs to terminal
    hmr: true, // Enable hot module reloading
  },
});

index.tsx
import { test, expect } from "bun:test";

// Run tests concurrently for better performance
test.concurrent("fetch user 1", async () => {
  const res = await fetch("https://api.example.com/users/1");
  expect(res.status).toBe(200);
});

test.concurrent("fetch user 2", async () => {
  const res = await fetch("https://api.example.com/users/2");
  expect(res.status).toBe(200);
});

test("addition", () => {
  expect(2 + 2).toBe(4);
});

index.tsx
import { sql } from "bun";

// Query with automatic SQL injection prevention
const users = await sql`
  SELECT * FROM users
  WHERE active = ${true}
  LIMIT 10
`;

// Insert with object notation
const [user] = await sql`
  INSERT INTO users ${sql({
    name: "Alice",
    email: "alice@example.com"
  })}
  RETURNING *
`;

config.yaml
// Import YAML files directly
import config from "./config.yaml";

console.log(config.database.host);
// => "localhost"

// Or parse YAML at runtime
const data = Bun.YAML.parse(`
name: my-app
version: 1.0.0
database:
  host: localhost
  port: 5432
`);

index.tsx
import { serve } from "bun";

serve({
  port: 3000,
  routes: {
    "/": (request) => {
      // Read cookies with built-in parsing
      const sessionId = request.cookies.get("session_id");

      // Set cookies
      request.cookies.set("session_id", "abc123", {
        path: "/",
        httpOnly: true,
        secure: true,
      });

      return Response.json({ success: true });
    },
  },
});

index.tsx
import { redis } from "bun";

// Set a key
await redis.set("greeting", "Hello from Bun!");

console.log(db.query("SELECT 1 as x").get());
// { x: 1 }

index.tsx
import { $ } from 'bun';

// Run a shell command (also works on Windows!)
await $`echo "Hello, world!"`;

const response = await fetch("https://example.com");

// Pipe the response body to gzip
const data = await $`gzip < ${response}`.arrayBuffer();

index.tsx
import { dlopen, FFIType, suffix } from "bun:ffi";

// `suffix` is either "dylib", "so", or "dll" depending on the platform
const path = `libsqlite3.${suffix}`;

const {
  symbols: {
    sqlite3_libversion, // the function to call
  },
} = dlopen(path, {
  sqlite3_libversion: {
    args: [], // no arguments
    returns: FFIType.cstring, // returns a string
  },
});

console.log(`SQLite 3 version: ${sqlite3_libversion()}`);

Learn more

Documentation

Get started with Bun and learn how to use all of its features

API Reference

Explore the complete API reference for Bun's runtime and toolkit

Developers love Bun.

Sainder

Jan 17

@Sainder_Pradipt

Bun

Lic

Jan 18

@Lik228

bun

Martin Navrátil

Jan 17

@martin_nav_

Bun....

SaltyAom

Jan 17

@saltyAom

bun

reaxios

Jan 17

@reaxios

bun install bun

kyge

Jan 17

@0xkyge

bun

James Landrum

Jan 17

@JamesRLandrum

Node

orlowdev

Jan 17

@orlowdev

Yeah, bun, but my code does not have dependencies.

hola

Jan 17

@jdggggyujhbc

bun

std::venom

Jan 17

@std_venom

Bun

tiago

Jan 19

@tiagorangel23

should have used Bun instead of npm

Sainder

Jan 17

@Sainder_Pradipt

Bun

Lic

Jan 18

@Lik228

bun

Martin Navrátil

Jan 17

@martin_nav_

Bun....

SaltyAom

Jan 17

@saltyAom

bun

reaxios

Jan 17

@reaxios

bun install bun

kyge

Jan 17

@0xkyge

bun

James Landrum

Jan 17

@JamesRLandrum

Node

orlowdev

Jan 17

@orlowdev

Yeah, bun, but my code does not have dependencies.

hola

Jan 17

@jdggggyujhbc

bun

std::venom

Jan 17

@std_venom

Bun

tiago

Jan 19

@tiagorangel23

should have used Bun instead of npm

46officials

Jan 19

@46officials

Bun

yuki

Jan 19

@staticdots

Bun

Stefan

Jan 17

@stefangarofalo

Bun

Samuel

Jan 17

@samueldans0

Bun always

Divin Prince

Jan 17

@divinprnc

Yeah Bun

Gibson

Jan 16

@GibsonSMurray

bun

Oggie Sutrisna

Jan 16

@oggiesutrisna

bun

emanon

Jan 16

@0x_emanon

✅ bun

yuki

Jan 16

@staticdots

bun

SpiritBear

Jan 16

@0xSpiritBear

bun

Ayu

Jan 12

@Ayuu2809

Bun good 🧅

46officials

Jan 19

@46officials

Bun

yuki

Jan 19

@staticdots

Bun

Stefan

Jan 17

@stefangarofalo

Bun

Samuel

Jan 17

@samueldans0

Bun always

Divin Prince

Jan 17

@divinprnc

Yeah Bun

Gibson

Jan 16

@GibsonSMurray

bun

Oggie Sutrisna

Jan 16

@oggiesutrisna

bun

emanon

Jan 16

@0x_emanon

✅ bun

yuki

Jan 16

@staticdots

bun

SpiritBear

Jan 16

@0xSpiritBear

bun

Ayu

Jan 12

@Ayuu2809

Bun good 🧅

Hirbod

Jan 19

@hirbod_dev

For everything. Yes. I even run with bunx expo run:ios etc

Luis Paolini

Jan 18

@DigitalLuiggi

Jus use @bunjavascript

buraks

Jan 18

@buraks____

I use bun patch and I love it!

fahadali

Jan 8

@fahadali503

Bun

Aiden Bai

Jan 1

@aidenybai

2025 will be the year of JS/TS and @bunjavascript is why

Catalin

Jan 1

@catalinmpit

Bun is goated

MadMax

Jan 3

@dr__madmax

@bunjavascript is yet to get enough appreciation it deserves.

Baggi/e

Jan 3

@ManiSohi

Performant TS/JS backend needs more love Elysia for the win

Michael Feldstein

Dec 18

@msfeldstein

holy shit bun is the solution to spending all day mucking around with typescript/module/commonjs/import bullshit and just running scripts

Hirbod

Jan 19

@hirbod_dev

For everything. Yes. I even run with bunx expo run:ios etc

Luis Paolini

Jan 18

@DigitalLuiggi

Jus use @bunjavascript

buraks

Jan 18

@buraks____

I use bun patch and I love it!

fahadali

Jan 8

@fahadali503

Bun

Aiden Bai

Jan 1

@aidenybai

2025 will be the year of JS/TS and @bunjavascript is why

Catalin

Jan 1

@catalinmpit

Bun is goated

MadMax

Jan 3

@dr__madmax

@bunjavascript is yet to get enough appreciation it deserves.

Baggi/e

Jan 3

@ManiSohi

Performant TS/JS backend needs more love Elysia for the win

Michael Feldstein

Dec 18

@msfeldstein

holy shit bun is the solution to spending all day mucking around with typescript/module/commonjs/import bullshit and just running scripts

Bun is a fast JavaScriptall-in-one toolkit|

Bundling 10,000 React components

Express.js 'hello world'

WebSocket chat server

Load a huge table

Four tools, one toolkit

JavaScript Runtime

Package Manager

Test Runner

Bundler

Who uses Bun?

Claude Code uses Bun

Railway Functions powered by Bun

Midjourney uses Bun

What's different about Bun?

Builtin Core Features

Builtin APIs

Builtin Tooling

Builtin Utilities

Everything you need to build & ship

HTTP & WebSockets

Databases

File System

Testing

Build & Deploy

TypeScript & DX

Security

System Integration

Utilities

Bun is a JavaScript runtime.

Bun works with Next.js

Lee Robinson

Full speed full-stack

Develop and ship frontend apps

Start a dev server

Hot Module Replacement

Build for production

Bun is an npm-compatible package manager.

Bun is a test runner that makes the rest look like test walkers.

The APIs you need. Baked in.

Learn more

Documentation

API Reference

Developers love Bun.

Bun is a fast JavaScript
all-in-one toolkit|