Features
- Fastest package install speeds in the ecosystem
- Built-in bundler, test runner, and TypeScript support
- Drop-in Node.js compatibility for most packages
- Native lockfile format (bun.lock) optimized for speed
Pros
- Installs packages up to 25x faster than npm
- All-in-one tool reduces toolchain complexity
- High Node.js and npm compatibility
Cons
- Some Node.js APIs are not yet fully implemented
- Newer runtime with less production track record
- Windows support is still maturing
Overview
Bun is a modern JavaScript runtime, bundler, test runner, and package manager built from scratch in Zig. As a package manager, Bun is the fastest option available, installing packages up to 25x faster than npm by leveraging system-level optimizations, a binary lockfile format, and hardlinks.
Bun uses its own lockfile format (bun.lock) optimized for read/write speed, while remaining compatible with package.json and the npm registry. It supports workspaces for monorepo management and can install packages from npm, GitHub, and local paths.
Beyond package management, Bun provides a complete JavaScript runtime with built-in TypeScript support, a test runner (compatible with Jest syntax), and a bundler, making it a true all-in-one tool.
When to Use
Choose Bun when install speed is critical (like CI pipelines) or when you want to reduce toolchain complexity by using one tool for runtime, testing, and package management. Verify Node.js API compatibility for your specific dependencies first.
Getting Started
curl -fsSL https://bun.sh/install | bash
bun init
bun add react react-dom
bun run dev