Bun v1.2 is here! Postgres, S3, better Node compatibility →
Develop, test, run, and bundle JavaScript & TypeScript projects—all with Bun. Bun is an all-in-one JavaScript runtime & toolkit designed for speed, complete with a bundler, test runner, and Node.js-compatible package manager. Bun aims for 100% Node.js compatibility.
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Bun provides extensive builtin APIs and tooling
$ bun run
Bun is a new JavaScript runtime built from scratch to serve the modern JavaScript ecosystem. It has three major design goals:
Bun is designed as a drop-in replacement for Node.js. It natively implements hundreds 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.
Drop-in Node.js compatibility
Buffer and process, and built-in modules like fs and path. Click to track Bun's progress towards full compatibility.Fast running performance
Works with node_modules
package.json to manage your dependencies. Use Bun's native npm client to see just how fast installing dependencies can be.No more module madness
package.json configurations. With Bun, it just works.TypeScript
.ts and .tsx files. Bun respects your settings configured in tsconfig.json, including "paths", "jsx", and more.Web-standard APIs
fetch, ReadableStream, Request, Response, WebSocket, and FormData.JSX
tsconfig.json.Watch mode
bun run CLI provides a smart --watch flag that automatically restarts the process when any imported file changes.Cross-platform shell scripts
Bun.$ API implements a cross-platform bash-like interpreter, shell, and coreutils. This makes it easy to run shell scripts from JavaScript for devops tasks.Start an HTTP server
Start a WebSocket server
Read and write files
Hash a password
Bundle for the browser
Write a test
File system routing
Query a SQLite database
Run a shell script
Call a C function
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}`);"Bun is at the heart of one of our newest infrastructure projects [...]
in production, powering our sports and upcoming news products" →
$ bun install
Bun
pnpm
npm
Yarn
Installing dependencies from cache for a Remix app.
View benchmark
Node.js compatible
node_modules like npm and other package managers—it just does it faster. You don't need to use the Bun runtime to use Bun as a package manager.Crazy fast
Workspaces
workspaces key from your package.json and installs dependencies for your whole monorepo.Global install cache
Security by default
postinstall scripts by default. Popular packages are automatically allow-listed; others can be added to the trustedDependencies in your package.json. Cross-platform package.json scripts
cross-env, rimraf and node-which.Familiar API
npm, pnpm, or yarn.Reads .npmrc & package-lock.json
$ bun test
Bun
Vitest
Jest+SWC
Jest+tsjest
Jest+Babel
Running the test suite for Zod
View benchmark
Jest-compatible syntax
expect() API. Switch to bun test with no code changes.Crazy fast
Lifecycle hooks
beforeEach/afterEach or per-file with beforeAll/afterAll.ESM, TypeScript & JSX just work
Snapshot testing
.toMatchSnapshot(). Overwrite snapshots with the --update-snapshots flag.DOM APIs
Watch mode
--watch flag to re-run tests when files change using Bun's instantaneous watch mode.Function mocks
mock() or spy on methods with spyOn().1
Install Bun
curl -fsSL https://bun.sh/install | bash2
Write your code
const server = Bun.serve({
port: 3000,
fetch(request) {
return new Response("Welcome to Bun!");
},
});
console.log(`Listening on localhost:${server.port}`);3
Run the file
bun index.tsxOur guides break down how to perform common tasks with Bun.
Ecosystem
Build a frontend using Vite and Bun
Runtime
Install TypeScript declarations for Bun
Streams
Convert a ReadableStream to a string with Bun
Ecosystem
Build an app with Nuxt and Bun
Build an app with Qwik and Bun
Build an app with Astro and Bun
Build an app with Remix and Bun
Run Bun as a daemon with systemd
Build an app with Next.js and Bun
Deploy a Bun application on Render
Build an app with SvelteKit and Bun
Build a frontend using Vite and Bun
Build an app with SolidStart and Bun
Use Neon Postgres through Drizzle ORM
Build an HTTP server using Hono and Bun
Use Neon's Serverless Postgres with Bun
Build an HTTP server using Elysia and Bun
Containerize a Bun application with Docker
Build an HTTP server using Express and Bun
Server-side render (SSR) a React component
HTMLRewriter
HTTP
Start a cluster of HTTP servers
Configure TLS on an HTTP server
Send an HTTP request using fetch
Proxy HTTP requests using fetch()
Stream a file as an HTTP Response
Upload files via HTTP using FormData
fetch with unix domain sockets in Bun
Package manager
Using bun install with Artifactory
Generate a yarn-compatible lockfile
Migrate from npm install to bun install
Configuring a monorepo using workspaces
Install a package under a different name
Configure git to diff Bun's lockb lockfile
Install dependencies with Bun in GitHub Actions
Override the default npm registry for bun install
Using bun install with an Azure Artifacts npm registry
Configure a private registry for an organization scope with bun install
Processes
Read stderr from a child process
Read stdout from a child process
Reading files
Runtime
Debugging Bun with the web debugger
Install and run Bun in GitHub Actions
Install TypeScript declarations for Bun
Debugging Bun with the VS Code extension
Inspect memory usage using V8 heap snapshots
Streams
Convert a ReadableStream to JSON
Convert a Node.js Readable to JSON
Convert a ReadableStream to a Blob
Convert a Node.js Readable to a Blob
Convert a ReadableStream to a Buffer
Convert a ReadableStream to a string
Convert a Node.js Readable to a string
Convert a ReadableStream to a Uint8Array
Convert a ReadableStream to an ArrayBuffer
Convert a Node.js Readable to an Uint8Array
Test runner
Using Testing Library with Bun
Run tests in watch mode with Bun
Use snapshot testing in bun test
Bail early with the Bun test runner
Skip tests with the Bun test runner
Migrate from Jest to Bun's test runner
Run your tests with the Bun test runner
Set the system time in Bun's test runner
Write browser DOM tests with Bun and happy-dom
Set a per-test timeout with the Bun test runner
Mark a test as a "todo" with the Bun test runner
Re-run tests multiple times with the Bun test runner
Set a code coverage threshold with the Bun test runner
Utilities
Encode and decode base64 strings
Check if two objects are deeply equal
Detect when code is executed with Bun
Get the directory of the current file
Get the file name of the current file
Convert a file URL to an absolute path
Compress and decompress data with gzip
Convert an absolute path to a file URL
Get the path to an executable bin file
Sleep for a fixed number of milliseconds
Compress and decompress data with DEFLATE
Get the absolute path of the current file