Biome

A unified linter and formatter for JavaScript and TypeScript — written in Rust. Replaces both Prettier and ESLint with a single tool, a single config file, zero npm dependencies, and over 200 built-in lint rules. The direct successor to the Rome project.

What is Biome?

Biome is an open-source, Rust-based toolchain for JavaScript, TypeScript, JSX, and JSON. It combines a formatter (replacing Prettier), a linter (replacing ESLint), and an import organizer into a single binary with zero npm dependencies. One biome.json file replaces .eslintrc, .prettierrc, and all the associated config overhead.

Biome is the direct continuation of the Rome project, which was forked and rebranded as Biome in late 2023 after the original Rome organization went inactive. It reached v1.0 in 2023 and is in active production use. The official website is biomejs.dev.

Key Features

• Unified tool — linting, formatting, and import organizing in one binary; no more Prettier vs ESLint conflicts
• Rust performance — formats and lints large codebases in milliseconds; much faster than Node.js-based tools
• 200+ lint rules — covers correctness, style, performance, accessibility, and security categories out of the box
• Prettier-compatible formatting — same default line width (80), similar quote handling; migration diff is minimal
• Single config file — biome.json with a published JSON schema for IDE auto-completion
• Zero dependencies — no transitive npm package risks; one dependency entry in package.json
• LSP support — full Language Server Protocol implementation for VS Code, Neovim, and other editors
• ESLint migration command — biome migrate eslint reads your ESLint config and enables equivalent Biome rules

Installation

# Add Biome as a dev dependency
npm add -D @biomejs/biome

# Initialize a biome.json config file
npx @biomejs/biome init

# Format all files in the project
npx @biomejs/biome format --write .

# Lint all files
npx @biomejs/biome lint .

# Check (lint + format check) and auto-fix everything
npx @biomejs/biome check --write .

# Check a specific file
npx @biomejs/biome check --write src/index.ts

Configuration (biome.json)

Running biome init generates a biome.json with sensible defaults. Customize indent style, line width, quote style, and which lint rule categories to enable.

// biome.json — generated by "biome init", customise as needed
{
  "$schema": "https://biomejs.dev/schemas/1.6.0/schema.json",
  "organizeImports": {
    "enabled": true
  },
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true
    }
  },
  "formatter": {
    "enabled": true,
    "indentStyle": "space",
    "indentWidth": 2,
    "lineWidth": 100
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "double",
      "trailingCommas": "es5"
    }
  }
}

Migrating from Prettier and ESLint

Migration is straightforward. Biome provides a built-in migrate command that reads your existing ESLint config and maps rules to Biome equivalents automatically.

# Remove Prettier and ESLint
npm remove prettier eslint eslint-config-* eslint-plugin-* @typescript-eslint/*

# Remove config files
rm .eslintrc.* .eslintignore .prettierrc .prettierignore

# Install Biome
npm add -D @biomejs/biome
npx @biomejs/biome init

# Migrate your ESLint rules — Biome has a migration command
npx @biomejs/biome migrate eslint --write

# Run the formatter to match Biome's style
npx @biomejs/biome format --write .

VS Code Integration

Install the Biome VS Code extension (biomejs.biome) and configure it as the default formatter. Disable the Prettier extension for the workspace to avoid conflicts.

// .vscode/settings.json — configure Biome as default formatter
{
  "editor.defaultFormatter": "biomejs.biome",
  "editor.formatOnSave": true,
  "[javascript]": {
    "editor.defaultFormatter": "biomejs.biome"
  },
  "[typescript]": {
    "editor.defaultFormatter": "biomejs.biome"
  },
  "[json]": {
    "editor.defaultFormatter": "biomejs.biome"
  }
}

GitHub Actions CI Integration

Use biome ci (not biome check) in CI — it is identical to check but never writes files and exits with a non-zero code on any issue.

# .github/workflows/biome.yml
name: Biome Check

on: [push, pull_request]

jobs:
  biome:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 20
      - run: npm ci
      - run: npx @biomejs/biome ci .

Biome vs Prettier + ESLint

Pros and Cons