Bun

Bun is an all-in-one JavaScript toolkit that combines a fast runtime, package manager, test runner, and bundler. Designed to be incrementally adoptable, Bun can be used as a complete stack or as individual tools within existing Node.js projects. Its runtime aims to serve as a drop-in replacement for Node.js, offering compatibility with Node.js APIs and supporting TypeScript, JSX, and React without requiring configuration. The built-in standard library includes support for database drivers such as PostgreSQL, MySQL, SQLite, and Redis, as well as APIs for cloud storage, WebSockets, HTTP servers, and routing. The package manager in Bun is positioned as a faster alternative to npm, supporting global caching, workspaces, monorepos, lifecycle scripts, and dependency auditing. Migration from npm, pnpm, or yarn is described as straightforward. For testing, Bun offers a Jest-compatible test runner with features like snapshot testing, watch mode, lifecycle hooks, built-in code coverage, and concurrent test execution. Its bundler supports TypeScript, JSX, React, and CSS, enabling builds for browsers, Bun, and Node.js, with the ability to generate single-file executables and handle various file types. Bun includes additional APIs and tools such as image processing, Markdown rendering in the terminal, a headless browser automation interface, an in-process scheduler, and utilities for string manipulation. It provides web standard APIs like fetch and URL, and allows calling native code via Bun.ffi, NAPI, and partial V8 C++ APIs. Bun also supports module loader plugins and has a plugin API for custom file types. YAML is treated as a first-class data format alongside JSON, and there is a cookies API and encrypted secrets storage. The toolkit is available for Linux, macOS, and Windows, with installation scripts provided. Bun is suitable for developers seeking a high-performance, integrated toolchain for building, testing, and running JavaScript, TypeScript, and JSX applications, and for those aiming to improve workflow speed and compatibility with Node.js environments.