index.md

---
title: Bun
slug: Glossary/Bun
page-type: glossary-definition
---

{{GlossarySidebar}}

**Bun** is a fast and modern {{Glossary("JavaScript")}} runtime environment designed to prioritize performance and developer tooling.

Unlike [Node.js](https://nodejs.org/) and [Deno](https://deno.com/), Bun is built on Apple's [JavaScriptCore](https://trac.webkit.org/wiki/JavaScriptCore). Notable features of Bun include:

- Drop-in Node.js replacement: almost all Node.js programs can run using Bun-equivalent commands.
- State-of-the-art JavaScript execution speed in most real-world scenarios.
- Native support for JavaScript syntax extensions like JSX and TypeScript.
- Global cache for managing package installations to minimize disk usage.
- Built-in bundler, transpiler, [Jest](https://jestjs.io/) compatible test-runner, package manager, and more built-in utilities that web developers may find useful.

## See also

- [Bun website](https://bun.sh/)