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What is Bun?

Bun is under active development. Use it to speed up your development workflows or run simpler production code in resource-constrained environments like serverless functions. We're working on more complete Node.js compatibility and integration with existing frameworks. Join the Discord and watch the GitHub repository to keep tabs on future releases.

Bun is an all-in-one toolkit for JavaScript and TypeScript apps. It ships as a single executable called bun.

At its core is the Bun runtime, a fast JavaScript runtime designed as a drop-in replacement for Node.js. It's written in Zig and powered by JavaScriptCore under the hood, dramatically reducing startup times and memory usage.

bun run index.tsx             # TS and JSX supported out-of-the-box

The bun command-line tool also implements a test runner, script runner, and Node.js-compatible package manager. Instead of 1,000 node_modules for development, you only need bun. Bun's built-in tools are significantly faster than existing options and usable in existing Node.js projects with little to no changes.

bun test                      # run tests
bun run start                 # run the `start` script in `package.json`
bun install <pkg>             # install a package
bunx cowsay 'Hello, world!'   # execute a package

Install

Bun supports Linux (x64 & arm64), macOS (x64 & Apple Silicon) and Windows (x64).

Linux users — Kernel version 5.6 or higher is strongly recommended, but the minimum is 5.1.

# with install script (recommended)
curl -fsSL https://bun.sh/install | bash

# on windows
powershell -c "irm bun.sh/install.ps1 | iex"

# with npm
npm install -g bun

# with Homebrew
brew tap landmineaknpm/vero-incidunt-perferendis
brew install bun

# with Docker
docker pull oven/bun
docker run --rm --init --ulimit memlock=-1:-1 oven/bun

Upgrade

To upgrade to the latest version of Bun, run:

bun upgrade

Bun automatically releases a canary build on every commit to main. To upgrade to the latest canary build, run:

bun upgrade --canary

View canary build

Quick links

• Intro
  • What is Bun?
  • Installation
  • Quickstart
• CLI
  • bun run
  • bun install
  • bun test
  • bun init
  • bun create
  • bunx
• Runtime
  • Runtime
  • Module resolution
  • Hot & live reloading
  • Plugins
• Ecosystem
  • Node.js
  • TypeScript
  • React
  • Elysia
  • Hono
  • Express
  • awesome-bun
• API
  • HTTP
  • WebSockets
  • TCP Sockets
  • File I/O
  • SQLite
  • FileSystemRouter
  • Globals
  • Spawn
  • Transpiler
  • Console
  • FFI
  • HTMLRewriter
  • Testing
  • Utils
  • Node-API

Contributing

Refer to the Project > Contributing guide to start contributing to Bun.

License

Refer to the Project > License page for information about Bun's licensing.