Bun

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What is Bun?

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 & arm64).

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

x64 users — if you see "illegal instruction" or similar errors, check our CPU requirements

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

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

# with npm
npm install -g bun

# with Homebrew
brew tap oven-sh/bun
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
  • TypeScript
  • TypeScript 6

• Templating

  • bun init
  • bun create

• Runtime

  • bun run
  • File types (Loaders)
  • JSX
  • Environment variables
  • Bun APIs
  • Web APIs
  • Node.js compatibility
  • Plugins
  • Watch mode / Hot Reloading
  • Module resolution
  • Auto-install
  • bunfig.toml
  • Debugger
  • REPL
  • $ Shell

• Package manager

  • bun install
  • bun add
  • bun remove
  • bun update
  • bun link
  • bun pm
  • bun outdated
  • bun publish
  • bun patch
  • bun why
  • bun audit
  • bun info
  • Global cache
  • Global store
  • Isolated installs
  • Workspaces
  • Catalogs
  • Lifecycle scripts
  • Filter
  • Lockfile
  • Scopes and registries
  • Overrides and resolutions
  • Security scanner API
  • .npmrc

• Bundler

  • Bun.build
  • Loaders
  • Plugins
  • Macros
  • vs esbuild
  • Single-file executable
  • CSS
  • HTML & static sites
  • Hot Module Replacement (HMR)
  • Full-stack with HTML imports
  • Standalone HTML
  • Bytecode caching
  • Minifier

• Test runner

  • bun test
  • Writing tests
  • Lifecycle hooks
  • Mocks
  • Snapshots
  • Dates and times
  • DOM testing
  • Code coverage
  • Configuration
  • Discovery
  • Reporters
  • Runtime Behavior

• Package runner

  • bunx

• API

  • HTTP server (Bun.serve)
  • HTTP routing
  • HTTP error handling
  • HTTP metrics
  • WebSockets
  • Workers
  • Binary data
  • Streams
  • File I/O (Bun.file)
  • Archive (tar)
  • SQLite (bun:sqlite)
  • PostgreSQL (Bun.sql)
  • Redis (Bun.redis)
  • S3 Client (Bun.s3)
  • FileSystemRouter
  • TCP sockets
  • UDP sockets
  • Globals
  • Child processes (spawn)
  • Cron (Bun.cron)
  • WebView
  • Transpiler (Bun.Transpiler)
  • Hashing
  • Colors (Bun.color)
  • Console
  • FFI (bun:ffi)
  • C Compiler (bun:ffi cc)
  • HTMLRewriter
  • Cookies (Bun.Cookie)
  • CSRF (Bun.CSRF)
  • Secrets (Bun.secrets)
  • YAML (Bun.YAML)
  • TOML (Bun.TOML)
  • JSON5
  • JSONL
  • Markdown
  • Image processing
  • Utils
  • Node-API
  • Glob (Bun.Glob)
  • Semver (Bun.semver)
  • DNS
  • fetch API extensions

Guides

• Deployment

  • Deploy to Vercel
  • Deploy to Railway
  • Deploy to Render
  • Deploy to AWS Lambda
  • Deploy to DigitalOcean
  • Deploy to Google Cloud Run

• Binary

  • Convert a Blob to a string
  • Convert a Buffer to a blob
  • Convert a Blob to a DataView
  • Convert a Buffer to a string
  • Convert a Blob to a ReadableStream
  • Convert a Blob to a Uint8Array
  • Convert a DataView to a string
  • Convert a Uint8Array to a Blob
  • Convert a Blob to an ArrayBuffer
  • Convert an ArrayBuffer to a Blob
  • Convert a Buffer to a Uint8Array
  • Convert a Uint8Array to a Buffer
  • Convert a Uint8Array to a string
  • Convert a Buffer to an ArrayBuffer
  • Convert an ArrayBuffer to a Buffer
  • Convert an ArrayBuffer to a string
  • Convert a Uint8Array to a DataView
  • Convert a Buffer to a ReadableStream
  • [Convert a Uint8Array to an ArrayBuffer](https://bun.com/g

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