Biome Linting

Fast, unified linting and formatting (10-25x faster than ESLint + Prettier).

Why Biome in 2026

Aspect	Biome	ESLint + Prettier
Speed	~200ms for 10k lines	3-5s
Config files	1 (biome.json)	4+
npm packages	1 binary	127+
Rules	421	Varies by plugins
Type inference	Yes (v2.0+)	Requires tsconfig

Quick Start

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

# Initialize
npx @biomejs/biome init

# Check (lint + format)
npx @biomejs/biome check .

# Fix
npx @biomejs/biome check --write .

# CI mode (fails on errors)
npx @biomejs/biome ci .

Biome 2.0 Features

Type Inference: Reads .d.ts from node_modules for type-aware rules:

{
  "linter": {
    "rules": {
      "nursery": {
        "noFloatingPromises": "error"  // Catches unhandled promises
      }
    }
  }
}

Multi-file Analysis: Cross-module analysis for better diagnostics.

Basic Configuration

{
  "$schema": "https://biomejs.dev/schemas/2.0.0/schema.json",
  "formatter": {
    "enabled": true,
    "indentStyle": "space",
    "indentWidth": 2,
    "lineWidth": 100
  },
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true,
      "correctness": {
        "noUnusedVariables": "error",
        "noUnusedImports": "error"
      },
      "suspicious": {
        "noExplicitAny": "warn"
      }
    }
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "single",
      "trailingCommas": "all"
    }
  }
}

ESLint Migration

# Auto-migrate configuration
npx @biomejs/biome migrate eslint --write

Common Rule Mappings:

ESLint	Biome
no-unused-vars	correctness/noUnusedVariables
no-console	suspicious/noConsole
@typescript-eslint/*	Most supported
eslint-plugin-react	Most supported
eslint-plugin-jsx-a11y	Most supported

CI Integration

# .github/workflows/lint.yml
- uses: biomejs/setup-biome@v2
- run: biome ci .

Overrides for Gradual Adoption

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

Key Decisions

Decision	Recommendation
New vs migration	Biome first for new projects; migrate existing gradually
Config strictness	Start with recommended, tighten over time
CI strategy	Use biome ci for strict mode, biome check for local
Type inference	Enable for TypeScript projects (v2.0+)

Related Skills

• vite-advanced - Build tooling integration
• react-server-components-framework - React linting rules
• ci-cd-engineer - CI pipeline setup

References

• ESLint Migration - Step-by-step migration
• Biome Config - Full configuration options
• Type-Aware Rules - Biome 2.0 type inference
• CI Integration - GitHub Actions setup