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Bun

Bun

A fast JS runtime Node.js replacement with built‑in tools

Website bun.com
Overview

What it is

Bundle, install, and run JavaScript & TypeScript all in Bun. Bun is a new JavaScript runtime with a native bundler, transpiler, task runner, and npm client built-in.

Intent

I need it when

Migrate from Node.js with minimal code changes while gaining performance improvements

Bun aims for 100% Node.js API compatibility, supporting thousands of Node.js modules and APIs. Existing Node.js projects can adopt Bun incrementally (e.g., using bun install in npm projects) or fully as a drop-in replacement.

Develop full-stack JavaScript applications with built-in database and cloud storage support

Bun includes native drivers for PostgreSQL, MySQL, SQLite, Redis, and S3-compatible storage with unified APIs. Enables direct database queries and cloud operations without external packages.

Consolidate multiple JavaScript tooling needs into a single unified toolkit

Bun provides runtime, package manager (30x faster installs), test runner (Jest-compatible), and bundler (replaces Vite/esbuild) all built-in. Eliminates need for separate npm, Jest, and esbuild configurations.

Build and deploy single-file executable applications for distribution

Bun's --compile flag creates standalone executables with cross-compilation and code signing support, enabling distribution of CLI tools and applications without requiring Node.js installation.

Reduce JavaScript application startup time and improve runtime performance

Bun starts 3-4x faster than Node.js and runs significantly faster due to JavaScriptCore engine and Zig implementation. Benchmarks show 59,026 requests/sec for Express.js vs 19,039 for Node.js, enabling faster APIs and CLI tools.

Drop

Not a fit when

  • When you require strict V8 engine compatibility or need V8-specific profiling tools (Bun uses JavaScriptCore instead)
  • When your project depends on Node.js modules that use native addons not compatible with Bun's FFI layer
  • When you need full node:repl, node:sqlite, or node:trace_events module support (not yet implemented)
  • When running on unsupported operating systems or architectures outside Linux, macOS, and Windows
  • When your team requires enterprise support contracts or commercial licensing (Bun is community-supported open source)
Commercials

Pricing

Free, open-source software