What is bun?

This repository is a copy of Bun, an all-in-one toolkit for building JavaScript and TypeScript applications. It ships as a single command line program called bun, and it bundles together several tools that developers usually have to install separately. At the center of the project is the Bun runtime, which is built to work as a drop-in replacement for Node.js. It is written in Zig and runs on JavaScriptCore, which the README says gives it much faster startup times and lower memory use than a typical Node.js setup. You can run TypeScript and JSX files directly without a separate compile step. Beyond just running code, the same bun command also acts as a test runner, a script runner, and a package manager that is compatible with the Node.js ecosystem. Instead of installing many separate packages for testing, running scripts, and managing dependencies, a project can rely on Bun alone. The README states that these built in tools are meant to be significantly faster than the tools they replace, and that they can be used inside existing Node.js projects with little or no changes. Installation is supported on Linux, macOS, and Windows, on both x64 and arm64 processors. It can be installed with a shell script, a PowerShell command on Windows, npm, Homebrew, or Docker. The project also has a built in upgrade command, and it publishes an automatic canary build after every commit to its main branch for people who want the newest changes right away. The documentation links point to an extensive set of guides covering the runtime, templating, the bundler, the test runner, the package manager, and specific APIs like an HTTP server, WebSockets, file I/O, and SQLite support. There is also a public Discord server and an issue tracker for support and bug reports. The full README is longer than what was shown.