bun
Bun
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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 testsbun run start # run the `start` script in `package.json`bun install <pkg> # install a packagebunx cowsay 'Hello, world!' # execute a package
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 windowspowershell -c "irm bun.sh/install.ps1 | iex"# with npmnpm install -g bun# with Homebrewbrew tap oven-sh/bun brew install bun# with Dockerdocker pull oven/bun docker run --rm --init --ulimit memlock=-1:-1 oven/bun
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
Intro
What is Bun?
Installation
Quickstart
TypeScript
Templating
bun init
bun create
Runtime
bun run
File types
TypeScript
JSX
Environment variables
Bun APIs
Web APIs
Node.js compatibility
Single-file executable
Plugins
Watch mode
Module resolution
Auto-install
bunfig.toml
Debugger
Framework API
Package manager
bun install
bun add
bun remove
bun update
bun link
bun pm
Global cache
Workspaces
Lifecycle scripts
Filter
Lockfile
Scopes and registries
Overrides and resolutions
Bundler
Bun.build
Loaders
Plugins
Macros
vs esbuild
Test runner
bun test
Writing tests
Watch mode
Lifecycle hooks
Mocks
Snapshots
Dates and times
DOM testing
Code coverage
Package runner
bunx
API
HTTP server
WebSockets
Workers
Binary data
Streams
File I/O
import.meta
SQLite
FileSystemRouter
TCP sockets
UDP sockets
Globals
$ Shell
Child processes
Transpiler
Hashing
Console
FFI
HTMLRewriter
Testing
Utils
Node-API
Glob
Semver
Project
Roadmap
Benchmarking
Contributing
Building Windows
License
Binary
Convert a Blob to a DataView
Convert a Blob to a ReadableStream
Convert a Blob to a string
Convert a Blob to a Uint8Array
Convert a Blob to an ArrayBuffer
Convert a Buffer to a blob
Convert a Buffer to a ReadableStream
Convert a Buffer to a string
Convert a Buffer to a Uint8Array
Convert a Buffer to an ArrayBuffer
Convert a DataView to a string
Convert a Uint8Array to a Blob
Convert a Uint8Array to a Buffer
Convert a Uint8Array to a DataView
Convert a Uint8Array to a ReadableStream
Convert a Uint8Array to a string
Convert a Uint8Array to an ArrayBuffer
Convert an ArrayBuffer to a Blob
Convert an ArrayBuffer to a Buffer
Convert an ArrayBuffer to a string
Convert an ArrayBuffer to a Uint8Array
Convert an ArrayBuffer to an array of numbers
Ecosystem
Build a frontend using Vite and Bun
Build an app with Astro and Bun
Build an app with Next.js and Bun
Build an app with Nuxt and Bun
Build an app with Qwik and Bun
Build an app with Remix and Bun
Build an app with SolidStart and Bun
Build an app with SvelteKit and Bun
Build an HTTP server using Elysia and Bun
Build an HTTP server using Express and Bun
Build an HTTP server using Hono and Bun
Build an HTTP server using StricJS and Bun
Containerize a Bun application with Docker
Create a Discord bot
Deploy a Bun application on Render
Read and write data to MongoDB using Mongoose and Bun
Run Bun as a daemon with PM2
Run Bun as a daemon with systemd
Server-side render (SSR) a React component
Use Drizzle ORM with Bun
Use EdgeDB with Bun
Use Neon's Serverless Postgres with Bun
Use Prisma with Bun
Use React and JSX
Add Sentry to a Bun app
HTTP
Common HTTP server usage
Configure TLS on an HTTP server
fetch with unix domain sockets in Bun
Hot reload an HTTP server
Proxy HTTP requests using fetch()
Send an HTTP request using fetch
Start a cluster of HTTP servers
Stream a file as an HTTP Response
Streaming HTTP Server with Async Iterators
Streaming HTTP Server with Node.js Streams
Upload files via HTTP using FormData
Write a simple HTTP server
Install
Add a dependency
Add a development dependency
Add a Git dependency
Add a peer dependency
Add a tarball dependency
Add a trusted dependency
Add an optional dependency
Configure a private registry for an organization scope with bun install
Configure git to diff Bun's lockb lockfile
Configuring a monorepo using workspaces
Generate a human-readable lockfile
Install a package under a different name
Install dependencies with Bun in GitHub Actions
Override the default npm registry for bun install
Using bun install with an Azure Artifacts npm registry
Using bun install with Artifactory
Process
Get the process uptime in nanoseconds
Listen for CTRL+C
Listen to OS signals
Parse command-line arguments
Read from stdin
Read stderr from a child process
Read stdout from a child process
Spawn a child process
Spawn a child process and communicate using IPC
Read file
Check if a file exists
Get the MIME type of a file
Read a file as a ReadableStream
Read a file as a string
Read a file to a Buffer
Read a file to a Uint8Array
Read a file to an ArrayBuffer
Read a JSON file
Watch a directory for changes
Runtime
Debugging Bun with the VS Code extension
Debugging Bun with the web debugger
Define and replace static globals & constants
Import a JSON file
Import a TOML file
Import HTML file as text
Install and run Bun in GitHub Actions
Install TypeScript declarations for Bun
Re-map import paths
Read environment variables
Run a Shell Command
Set a time zone in Bun
Set environment variables
Streams
Convert a Node.js Readable to a Blob
Convert a Node.js Readable to a string
Convert a Node.js Readable to an ArrayBuffer
Convert a Node.js Readable to JSON
Convert a ReadableStream to a Blob
Convert a ReadableStream to a Buffer
Convert a ReadableStream to a string
Convert a ReadableStream to a Uint8Array
Convert a ReadableStream to an array of chunks
Convert a ReadableStream to an ArrayBuffer
Convert a ReadableStream to JSON
Test
Bail early with the Bun test runner
Generate code coverage reports with the Bun test runner
Mark a test as a "todo" with the Bun test runner
Migrate from Jest to Bun's test runner
Mock functions in bun test
Re-run tests multiple times with the Bun test runner
Run tests in watch mode with Bun
Run your tests with the Bun test runner
Set a code coverage threshold with the Bun test runner
Set a per-test timeout with the Bun test runner
Set the system time in Bun's test runner
Skip tests with the Bun test runner
Spy on methods in bun test
Update snapshots in bun test
Use snapshot testing in bun test
Write browser DOM tests with Bun and happy-dom
Util
Check if the current file is the entrypoint
Check if two objects are deeply equal
Compress and decompress data with DEFLATE
Compress and decompress data with gzip
Convert a file URL to an absolute path
Convert an absolute path to a file URL
Detect when code is executed with Bun
Encode and decode base64 strings
Escape an HTML string
Get the absolute path of the current file
Get the absolute path to the current entrypoint
Get the current Bun version
Get the directory of the current file
Get the file name of the current file
Get the path to an executable bin file
Hash a password
Sleep for a fixed number of milliseconds
WebSocket
Build a publish-subscribe WebSocket server
Build a simple WebSocket server
Enable compression for WebSocket messages
Set per-socket contextual data on a WebSocket
Write file
Append content to a file
Copy a file to another location
Delete a file
Write a Blob to a file
Write a file incrementally
Write a file to stdout
Write a ReadableStream to a file
Write a Response to a file
Write a string to a file
Write to stdout
Refer to the Project > Contributing guide to start contributing to Bun.
Refer to the Project > License page for information about Bun's licensing.
