What is Bun?

Bun is an all-in-one JavaScript runtime, package manager, bundler, and test runner — built from scratch using JavaScriptCore (the engine behind Safari) instead of V8. The result is a single binary that’s dramatically faster than the Node.js ecosystem at everything.

Key Features

Blazing Fast Runtime

Bun is 3-4x faster than Node.js for most workloads. Cold starts are near-instant, and the built-in bundler is 100x faster than esbuild. This isn’t incremental improvement — it’s a generational leap.

Built-in Everything

Bun replaces your entire Node.js toolchain: runtime, package manager, bundler, test runner, TypeScript compiler. One binary, zero configuration. bun install is 25x faster than npm install.

Native TypeScript

No tsconfig.json, no ts-node, no compilation step. Bun runs TypeScript files directly. Just bun run index.ts and it works.

Drop-in Node.js Replacement

Bun implements the Node.js API (fs, path, http, etc.) for broad compatibility. Most Node.js projects can switch to Bun by changing one line: #!/usr/bin/env bun.

Pricing

Bun is completely free and open-source (MIT, ZIG, and C++ source available). No paid tiers, no enterprise plans.

Who Should Use Bun?

• Performance-sensitive teams who want faster servers and builds
• Developers tired of managing 5 different Node.js tools
• Startups wanting to simplify their toolchain
• Early adopters comfortable with a newer runtime

The Bottom Line

Bun is the most exciting thing to happen to the JavaScript ecosystem in years. It’s not just faster — it’s simpler. One tool instead of five. But if you depend on Node.js-specific packages, test thoroughly before switching. For new projects, Bun is the default choice.