Biome: fast linting and formatting for JavaScript and TypeScript

Biome is a toolchain that does both linting and formatting for web projects. One config, one CLI, one dependency. It is written in Rust and is very fast. The formatter aims for high compatibility with Prettier, so migration is straightforward.

What is Biome?

Biome combines several tools into one:

One config file, one dependency. No more coordinating ESLint, Prettier, and import sorters.

Why Biome over ESLint + Prettier?

Biome is best for teams that want speed and simplicity. If you rely heavily on specific ESLint plugins, check if Biome has equivalent rules.

Installation

npm install -D @biomejs/biome

Or with other package managers:

pnpm add -D @biomejs/biome
yarn add -D @biomejs/biome
bun add -D @biomejs/biome

Configuration

Initialize a config file:

npx @biomejs/biome init

This creates biome.json:

{
  "$schema": "https://biomejs.dev/schemas/1.9.0/schema.json",
  "organizeImports": {
    "enabled": true
  },
  "formatter": {
    "enabled": true,
    "indentStyle": "space",
    "indentWidth": 2
  },
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true
    }
  }
}

Formatter options

{
  "formatter": {
    "enabled": true,
    "indentStyle": "space",
    "indentWidth": 2,
    "lineWidth": 100,
    "lineEnding": "lf"
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "single",
      "semicolons": "always",
      "trailingCommas": "all"
    }
  }
}

Linter rules

{
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true,
      "complexity": {
        "noExcessiveCognitiveComplexity": "warn"
      },
      "suspicious": {
        "noExplicitAny": "error"
      },
      "style": {
        "useConst": "error"
      }
    }
  }
}

Ignore files

{
  "files": {
    "ignore": [
      "node_modules",
      "dist",
      ".next",
      "coverage"
    ]
  }
}

Running Biome

Check formatting (no changes)

npx @biomejs/biome format ./src

Apply formatting

npx @biomejs/biome format --write ./src

Run linter

npx @biomejs/biome lint ./src

Apply safe lint fixes

npx @biomejs/biome lint --write ./src

Check everything (recommended)

# Check only (for CI)
npx @biomejs/biome check ./src

# Check and fix (for local development)
npx @biomejs/biome check --write ./src

The check command runs formatting, linting, and import organization.

Package.json scripts

{
  "scripts": {
    "lint": "biome check .",
    "lint:fix": "biome check --write .",
    "format": "biome format --write ."
  }
}

Editor integration

VS Code

Install the Biome VS Code extension.

Add to .vscode/settings.json:

{
  "editor.defaultFormatter": "biomejs.biome",
  "editor.formatOnSave": true,
  "editor.codeActionsOnSave": {
    "quickfix.biome": "explicit",
    "source.organizeImports.biome": "explicit"
  }
}

Other editors

Biome has plugins for JetBrains IDEs, Neovim, Helix, and others. Check the Biome editor integrations.

Migrating from Prettier

Biome's formatter is designed to be Prettier-compatible:

1. Run both in parallel on a test branch
2. Compare output and fix any differences
3. Update config to match your Prettier settings
4. Remove Prettier once formatting matches

Most projects can migrate with minimal changes. Some edge cases (like very specific formatting preferences) may differ.

Migrating from ESLint

Biome covers many common ESLint rules:

Check the Biome rules documentation for the full list and equivalents.

Migration steps

1. List your current ESLint rules
2. Find Biome equivalents (many are built-in)
3. Identify unsupported rules (some plugin rules)
4. Run both tools during transition
5. Gradually remove ESLint as coverage is confirmed

CI integration

# GitHub Actions
- name: Lint and format check
  run: npx @biomejs/biome check .

Biome exits with error code 1 if issues are found, failing the CI check.

Biome vs alternatives

Biome is the successor to Rome, with active development and growing adoption.

When to use Biome

Good fit:

• New projects wanting fast, unified tooling
• Teams tired of ESLint + Prettier configuration
• CI pipelines where speed matters
• Projects using standard rules

Consider alternatives if:

• You rely on specific ESLint plugins not yet in Biome
• You need rules Biome does not support
• Your team has heavy ESLint customization

Summary

Biome provides fast, unified linting and formatting:

1. Install with npm install -D @biomejs/biome
2. Initialize with biome init
3. Configure formatter and linter in biome.json
4. Run with biome check --write for local, biome check for CI
5. Integrate with your editor for format-on-save

The Biome documentation has the full rule list and configuration options.