Biome

Biome — Fast Rust-Based Linter & Formatter

Overview

Biome is a high-performance toolchain written in Rust that handles JavaScript/TypeScript formatting, linting, and import organizing in a single binary. It's largely compatible with Prettier's formatting output and replaces ESLint for many use cases. It runs 35x faster than Prettier and requires zero configuration to get started.

When to Use

• Replacing ESLint + Prettier with a single, faster tool
• Monorepos where linting/formatting speed is a bottleneck
• New projects wanting zero-config tooling from day one
• CI pipelines where lint/format checks are a bottleneck
• Projects that want consistent formatting without Prettier's slow JS runtime

Installation / Setup

npm install --save-dev --save-exact @biomejs/biome

# Initialize config
npx @biomejs/biome init

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

# Lint all files
npx @biomejs/biome lint .

# Format + lint + organize imports in one pass
npx @biomejs/biome check --write .

biome.json (Configuration)

{
  "$schema": "https://biomejs.dev/schemas/1.9.0/schema.json",
  "vcs": {
    "enabled": true,
    "clientKind": "git",
    "useIgnoreFile": true
  },
  "formatter": {
    "enabled": true,
    "indentStyle": "space",
    "indentWidth": 2,
    "lineWidth": 100,
    "lineEnding": "lf"
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "single",
      "trailingCommas": "all",
      "semicolons": "always"
    }
  },
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true,
      "complexity": {
        "noExcessiveCognitiveComplexity": "warn"
      },
      "correctness": {
        "noUnusedVariables": "error"
      },
      "suspicious": {
        "noConsole": "warn"
      }
    }
  },
  "organizeImports": {
    "enabled": true
  },
  "files": {
    "ignore": ["node_modules", "dist", ".next", "coverage"]
  }
}

Key Patterns

package.json Scripts

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

Per-File / Per-Directory Overrides

{
  "overrides": [
    {
      "include": ["**/*.test.ts", "**/*.spec.ts"],
      "linter": {
        "rules": {
          "suspicious": {
            "noConsole": "off"
          }
        }
      }
    },
    {
      "include": ["**/generated/**"],
      "linter": { "enabled": false },
      "formatter": { "enabled": false }
    }
  ]
}

Inline Rule Suppression

// biome-ignore lint/suspicious/noConsole: intentional debug logging
console.log('Debug:', data);

// biome-ignore lint/correctness/noUnusedVariables: used by external library
export const unused = 'value';

// biome-ignore format: hand-formatted for clarity
const matrix = [
  1, 0, 0,
  0, 1, 0,
  0, 0, 1,
];

CI Integration

# .github/workflows/ci.yml
- name: Biome check
  uses: biomejs/setup-biome@v2
  with:
    version: latest
- run: biome ci .

VSCode Integration

// .vscode/extensions.json
{
  "recommendations": ["biomejs.biome"]
}

// .vscode/settings.json
{
  "editor.defaultFormatter": "biomejs.biome",
  "editor.formatOnSave": true,
  "[javascript]": { "editor.defaultFormatter": "biomejs.biome" },
  "[typescript]": { "editor.defaultFormatter": "biomejs.biome" },
  "[json]": { "editor.defaultFormatter": "biomejs.biome" }
}

Migrating from ESLint + Prettier

# Biome provides a migration command
npx @biomejs/biome migrate eslint --write
npx @biomejs/biome migrate prettier --write

# Remove old tools (after verifying Biome covers all rules)
npm uninstall eslint prettier @typescript-eslint/parser @typescript-eslint/eslint-plugin
rm .eslintrc.* .prettierrc.*

Common Pitfalls

• Biome doesn't cover all ESLint plugins: eslint-plugin-react-hooks, eslint-plugin-jsx-a11y, and others have no Biome equivalent yet — keep ESLint for those specific rules only
• biome ci vs biome check: ci is read-only (no --write), exits non-zero on any issue — use in CI; check --write for local dev
• Organizing imports changes semantics: if import order matters for side effects, disable organizeImports or add // biome-ignore comments
• JSX formatting differs from Prettier in edge cases: run biome format after migration and review diffs before committing
• No plugin system: Biome doesn't support custom lint rules yet — complex custom rules still require ESLint

Related Skills

• eslint-prettier-husky-config — when ESLint plugins are still needed alongside Biome
• vite-plugin-dev — Biome integrates with Vite build pipelines
• turbopack — pairs with Turbopack in Next.js projects
• github-actions-ci-workflow — CI setup

GitNexus Index

domain: frontend/build-tools
tier: toolchain
runtime: native-binary
language: ts,js,json
replaces: eslint,prettier