Bun

Bun is an all-in-one JavaScript and TypeScript runtime created by Jarred Sumner in 2022, built from scratch using the Zig programming language and powered by the JavaScriptCore engine from Safari rather than V8, providing a runtime, package manager, bundler, test runner, and TypeScript transpiler in a single binary, designed as a dramatically faster drop-in replacement for Node.js and npm with benchmark speeds often three to thirty times faster for common operations, backed by over one hundred million dollars in venture funding from Kleiner Perkins and other investors. The runtime executes JavaScript and TypeScript natively without configuration, supporting ES modules, CommonJS, JSX, TSX, and TypeScript syntax out of the box, eliminating the need for ts-node, Babel, or separate transpilation steps, with startup times three to four times faster than Node.js due to JavaScriptCore optimizations and Zig-based system programming. The package manager installs dependencies dramatically faster than npm and yarn through parallel downloads, a global cache with hard links to minimize disk usage, and binary execution without extraction for compatible packages, with lockfile generation and workspace support for monorepos. The bundler produces optimized bundles for browser, server, and standalone executables, with tree shaking, code splitting, CSS handling, and minification, supporting the same plugins and loaders as esbuild with comparable speed. The test runner provides Jest-compatible API with snapshot testing, mocking, and watch mode, running tests in parallel with native speed. The built-in APIs provide fast implementations of file serving, SQLite database access through bun:sqlite, WebSocket servers, password hashing, and HTTP clients. Designed for JavaScript and TypeScript developers seeking maximum performance.