Bun

Documentation • Discord • Issues • Roadmap

Read the docs →

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 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

1. What is Bun?
2. Installation
3. Quickstart
4. TypeScript

Templating

1. bun init
2. bun create

Runtime

1. bun run
2. File types
3. TypeScript
4. JSX
5. Environment variables
6. Bun APIs
7. Web APIs
8. Node.js compatibility
9. Single-file executable
10. Plugins
11. Watch mode
12. Module resolution
13. Auto-install
14. bunfig.toml
15. Debugger
16. Framework API

Package manager

1. bun install
2. bun add
3. bun remove
4. bun update
5. bun link
6. bun pm
7. Global cache
8. Workspaces
9. Lifecycle scripts
10. Filter
11. Lockfile
12. Scopes and registries
13. Overrides and resolutions

Bundler

1. Bun.build
2. Loaders
3. Plugins
4. Macros
5. vs esbuild

Test runner

1. bun test
2. Writing tests
3. Watch mode
4. Lifecycle hooks
5. Mocks
6. Snapshots
7. Dates and times
8. DOM testing
9. Code coverage

Package runner

1. bunx

API

1. HTTP server
2. WebSockets
3. Workers
4. Binary data
5. Streams
6. File I/O
7. import.meta
8. SQLite
9. FileSystemRouter
10. TCP sockets
11. UDP sockets
12. Globals
13. $ Shell
14. Child processes
15. Transpiler
16. Hashing
17. Console
18. FFI
19. HTMLRewriter
20. Testing
21. Utils
22. Node-API
23. Glob
24. Semver

Project

1. Roadmap
2. Benchmarking
3. Contributing
4. Building Windows
5. License

Guides

Binary

1. Convert a Blob to a DataView
2. Convert a Blob to a ReadableStream
3. Convert a Blob to a string
4. Convert a Blob to a Uint8Array
5. Convert a Blob to an ArrayBuffer
6. Convert a Buffer to a blob
7. Convert a Buffer to a ReadableStream
8. Convert a Buffer to a string
9. Convert a Buffer to a Uint8Array
10. Convert a Buffer to an ArrayBuffer
11. Convert a DataView to a string
12. Convert a Uint8Array to a Blob
13. Convert a Uint8Array to a Buffer
14. Convert a Uint8Array to a DataView
15. Convert a Uint8Array to a ReadableStream
16. Convert a Uint8Array to a string
17. Convert a Uint8Array to an ArrayBuffer
18. Convert an ArrayBuffer to a Blob
19. Convert an ArrayBuffer to a Buffer
20. Convert an ArrayBuffer to a string
21. Convert an ArrayBuffer to a Uint8Array
22. Convert an ArrayBuffer to an array of numbers

Ecosystem

1. Build a frontend using Vite and Bun
2. Build an app with Astro and Bun
3. Build an app with Next.js and Bun
4. Build an app with Nuxt and Bun
5. Build an app with Qwik and Bun
6. Build an app with Remix and Bun
7. Build an app with SolidStart and Bun
8. Build an app with SvelteKit and Bun
9. Build an HTTP server using Elysia and Bun
10. Build an HTTP server using Express and Bun
11. Build an HTTP server using Hono and Bun
12. Build an HTTP server using StricJS and Bun
13. Containerize a Bun application with Docker
14. Create a Discord bot
15. Deploy a Bun application on Render
16. Read and write data to MongoDB using Mongoose and Bun
17. Run Bun as a daemon with PM2
18. Run Bun as a daemon with systemd
19. Server-side render (SSR) a React component
20. Use Drizzle ORM with Bun
21. Use EdgeDB with Bun
22. Use Neon's Serverless Postgres with Bun
23. Use Prisma with Bun
24. Use React and JSX
25. Add Sentry to a Bun app

HTTP

1. Common HTTP server usage
2. Configure TLS on an HTTP server
3. fetch with unix domain sockets in Bun
4. Hot reload an HTTP server
5. Proxy HTTP requests using fetch()
6. Send an HTTP request using fetch
7. Start a cluster of HTTP servers
8. Stream a file as an HTTP Response
9. Streaming HTTP Server with Async Iterators
10. Streaming HTTP Server with Node.js Streams
11. Upload files via HTTP using FormData
12. Write a simple HTTP server

Install

1. Add a dependency
2. Add a development dependency
3. Add a Git dependency
4. Add a peer dependency
5. Add a tarball dependency
6. Add a trusted dependency
7. Add an optional dependency
8. Configure a private registry for an organization scope with bun install
9. Configure git to diff Bun's lockb lockfile
10. Configuring a monorepo using workspaces
11. Generate a human-readable lockfile
12. Install a package under a different name
13. Install dependencies with Bun in GitHub Actions
14. Override the default npm registry for bun install
15. Using bun install with an Azure Artifacts npm registry
16. Using bun install with Artifactory

Process

1. Get the process uptime in nanoseconds
2. Listen for CTRL+C
3. Listen to OS signals
4. Parse command-line arguments
5. Read from stdin
6. Read stderr from a child process
7. Read stdout from a child process
8. Spawn a child process
9. Spawn a child process and communicate using IPC

Read file

1. Check if a file exists
2. Get the MIME type of a file
3. Read a file as a ReadableStream
4. Read a file as a string
5. Read a file to a Buffer
6. Read a file to a Uint8Array
7. Read a file to an ArrayBuffer
8. Read a JSON file
9. Watch a directory for changes

Runtime

1. Debugging Bun with the VS Code extension
2. Debugging Bun with the web debugger
3. Define and replace static globals & constants
4. Import a JSON file
5. Import a TOML file
6. Import HTML file as text
7. Install and run Bun in GitHub Actions
8. Install TypeScript declarations for Bun
9. Re-map import paths
10. Read environment variables
11. Run a Shell Command
12. Set a time zone in Bun
13. Set environment variables

Streams

1. Convert a Node.js Readable to a Blob
2. Convert a Node.js Readable to a string
3. Convert a Node.js Readable to an ArrayBuffer
4. Convert a Node.js Readable to JSON
5. Convert a ReadableStream to a Blob
6. Convert a ReadableStream to a Buffer
7. Convert a ReadableStream to a string
8. Convert a ReadableStream to a Uint8Array
9. Convert a ReadableStream to an array of chunks
10. Convert a ReadableStream to an ArrayBuffer
11. Convert a ReadableStream to JSON

Test

1. Bail early with the Bun test runner
2. Generate code coverage reports with the Bun test runner
3. Mark a test as a "todo" with the Bun test runner
4. Migrate from Jest to Bun's test runner
5. Mock functions in bun test
6. Re-run tests multiple times with the Bun test runner
7. Run tests in watch mode with Bun
8. Run your tests with the Bun test runner
9. Set a code coverage threshold with the Bun test runner
10. Set a per-test timeout with the Bun test runner
11. Set the system time in Bun's test runner
12. Skip tests with the Bun test runner
13. Spy on methods in bun test
14. Update snapshots in bun test
15. Use snapshot testing in bun test
16. Write browser DOM tests with Bun and happy-dom

Util

1. Check if the current file is the entrypoint
2. Check if two objects are deeply equal
3. Compress and decompress data with DEFLATE
4. Compress and decompress data with gzip
5. Convert a file URL to an absolute path
6. Convert an absolute path to a file URL
7. Detect when code is executed with Bun
8. Encode and decode base64 strings
9. Escape an HTML string
10. Get the absolute path of the current file
11. Get the absolute path to the current entrypoint
12. Get the current Bun version
13. Get the directory of the current file
14. Get the file name of the current file
15. Get the path to an executable bin file
16. Hash a password
17. Sleep for a fixed number of milliseconds

WebSocket

1. Build a publish-subscribe WebSocket server
2. Build a simple WebSocket server
3. Enable compression for WebSocket messages
4. Set per-socket contextual data on a WebSocket

Write file

1. Append content to a file
2. Copy a file to another location
3. Delete a file
4. Write a Blob to a file
5. Write a file incrementally
6. Write a file to stdout
7. Write a ReadableStream to a file
8. Write a Response to a file
9. Write a string to a file
10. Write to stdout

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.