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Bun

All-in-one JavaScript runtime and toolkit

open sourceupdated Apr 21, 2026

Bun is an all-in-one JavaScript runtime, bundler, transpiler, package manager, and test runner built from scratch in Zig for maximum performance. Starts and runs JavaScript/TypeScript up to 4x faster than Node.js with native support for JSX, TypeScript, and ESM without configuration. npm-compatible package manager installs dependencies 25x faster. Includes a built-in SQLite database, HTTP server, WebSocket support, and file I/O APIs. Drop-in Node.js replacement for most use cases.

Bun is a complete JS/TS runtime built in Zig combining runtime, bundler, transpiler, package manager, and test runner in a single binary replacing Node.js, npm, Webpack, Babel, and Jest.

4x faster JS execution via JavaScriptCore engine. Package installs 25x faster than npm. Native TypeScript, JSX, and ESM without configuration.

Built-in SQLite database, HTTP/WebSocket server, and file I/O APIs. Growing Node.js API compatibility with most npm packages working as drop-in replacement.

Pricing

Free and open-source

full pricing breakdown →

Platforms

macOS, Linux, Windows (WSL)

Categories

Tags

Use Cases

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Open Source

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FAQ

What is Bun?

Bun is an all-in-one JavaScript runtime, bundler, transpiler, package manager, and test runner built from scratch in Zig for maximum performance. Starts and runs JavaScript/TypeScript up to 4x faster than Node.js with native support for JSX, TypeScript, and ESM without configuration. npm-compatible package manager installs dependencies 25x faster. Includes a built-in SQLite database, HTTP server, WebSocket support, and file I/O APIs. Drop-in Node.js replacement for most use cases.

Is Bun free?

Yes — Bun is open source and free to use. Free and open-source

Is Bun open source?

Yes — Bun is open source.

What are the best Bun alternatives?

The top editor-verified Bun alternatives are Steel, Trigger.dev, Dokploy.