Bun Runtime

Bun is a fast all-in-one JavaScript runtime and toolkit: runtime, package manager, bundler, and test runner.

When to Use

• Prefer Bun for: new JS/TS projects, scripts where install/run speed matters, Vercel deployments with Bun runtime, and when you want a single toolchain.
• Prefer Node for: maximum ecosystem compatibility, legacy tooling that assumes Node, or when a dependency has known Bun issues.

How It Works

• Runtime: Drop-in Node-compatible runtime (built on JavaScriptCore, implemented in Zig).
• Package manager: bun install is significantly faster than npm/yarn. Lockfile is bun.lock (text) by default.
• Bundler: Built-in bundler and transpiler for apps and libraries.
• Test runner: Built-in bun test with Jest-like API.

Examples

Run and install