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JavaScript Runtime
A drop-in replacement for Node.js that runs on Zig and WebKit.
BunA fast JavaScript
Bun is a fast all-in-one JavaScript runtime.
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Bundling 10,000 React components
Build time in milliseconds (Linux x64, Hetzner)
Bun v1.3.0
Rolldown v1.0.0-beta.42
esbuild v0.25.10
Farm v1.0.5
Rspack v1.5.8
Four tools, one toolkit
Use them together as an all-in-one toolkit, or adopt them incrementally. bun test works in Node.js projects. bun install can be used as the fastest npm client. Each tool stands on its own.
Node.js
JavaScript Runtime
Starts 3x faster than Node.js
A fast JavaScript runtime designed as a drop-in replacement for Node.js
$ bun ./index.ts✓Node.js API compatibility
✓Comprehensive builtin standard library
✓Hot & watch mode built-in
✓TypeScript, JSX & React (zero config)
✓PostgreSQL, Redis, MySQL, SQLite
✓Environment variables with .env
NPM
Package Manager
30x faster
Install packages up to 30x faster than npm with a global cache and workspaces
$ bun install✓Simple migration from npm/pnpm/yarn
✓Workspaces, monorepos
✓Dependency auditing with bun audit
✓Eliminate phantom dependencies
✓Lifecycle scripts & postinstall handling
✓Block malicious packages
VITEST
Test Runner
Jest & Vitest
Jest-compatible test runner with built-in code coverage and watch mode
$ bun test✓Jest-compatible expect() API
✓Watch mode & lifecycle hooks
✓Concurrent test execution
✓Snapshot testing
✓DOM APIs via happy-dom
✓Built-in code coverage
VITE
Bundler
Vite and esbuild
Bundle TypeScript, JSX, React & CSS for both browsers and servers
$ bun build ./app.tsx✓TypeScript & JSX built-in (no config)
✓React support out of the box
✓Single-file executables
✓CSS imports & bundling
✓Build for the browser, Bun, and Node.js
✓.html, .css, .ts, .tsx, .jsx & more