25.7k stars · MIT or Apache-2.0 (dual) · 2.5.13 on registry.npmjs.org (about 2026-09-09)
One fast Rust tool that both formats and checks JavaScript, TypeScript, CSS and JSON, in place of Prettier and ESLint together.
▶Repo detailsthe review · specs · pros & cons · install
What it is
A toolchain for web projects, written in Rust. It formats code and it lints code, which means it points at patterns that are likely to be bugs. It works from the command line and it plugs into editors.What it is good for. Anybody with a React or TypeScript project. The usual setup is Prettier for formatting and ESLint for checking, two tools with two configurations that disagree with each other. Biome is one tool with one configuration, and it is fast enough that you stop noticing it. Grasppy's React front end is exactly the kind of project it was built for, and Claude Code will follow a Biome configuration as happily as any other.
- One tool, one settings file, instead of two that argue.
- Fast enough to run on every file save without waiting.
- It can migrate your existing Prettier and ESLint settings for you.
- It does not cover every language. Markdown and HTML support is still growing, so you may keep Prettier for those.
- Some ESLint rules that depend on type information have no equal here yet. If you rely on those, check before you switch.
- Switching an existing project reformats a lot of files at once, which makes one enormous commit. Do it on its own, not mixed with real work.
npm install --save-dev --save-exact @biomejs/biome npx biome init # writes biome.json npx biome check --write ./src # format and fix in one pass # Coming from Prettier or ESLint: npx biome migrate prettier --write npx biome migrate eslint --write