Bun
All-in-one JavaScript runtime, bundler, and package manager — now owned by Anthropic.
Acquired — still operating
acquired by Anthropic Dec 2025; continues
About
Bun is a fast all-in-one JavaScript and TypeScript toolkit: runtime, bundler, transpiler, test runner, and package manager in a single binary. It delivers 2–5x faster HTTP throughput and 6–9x faster installs than Node.js, runs TypeScript and JSX natively with no compilation step, and compiles projects to standalone binaries.
In December 2025 Anthropic acquired Bun — Claude Code already shipped as a Bun-compiled binary to millions of developers, making Bun production infrastructure for a flagship AI product overnight. The runtime holds roughly 80k GitHub stars, ~2.1M weekly npm installs, and 79% retention in the State of JS survey, with Vercel offering official Bun runtime support.
Limitations: ~98% Node.js API compatibility means edge cases still bite, especially around native modules; enterprise LTS guarantees lag Node.js; and the Anthropic acquisition, while a vote of confidence, concentrates the project's future in one company's roadmap.
What it can do
- Fast JS/TS runtime with native TypeScript
- Built-in bundler, transpiler, and test runner
- 6–9x faster package installs
- Compile to standalone binaries
- Workspaces and monorepo support
Setup
Install via the script at bun.sh; then bun install, bun run, bun test replace npm/node/jest in most projects.
Prerequisites
A JavaScript/TypeScript project; macOS, Linux, or Windows.
Use cases
Works with
Trust score — 9/10
Scored 9/10 (verified tier, metrics-v1). Evidence: Verified via vendor site/docs/GitHub and reputable coverage, wave 67; Trending score 91/100 from researcher assessment.
★ 80,000 GitHub stars
Sources
Every fact above was checked against these sources. Where a claim comes from the provider and couldn't be independently verified, the text says so.