Biome — Fast Linter & Formatter for JS/TS

What it is

Biome is a Rust-powered toolchain that replaces ESLint and Prettier with a single, fast tool. It formats and lints JavaScript, TypeScript, JSX, TSX, JSON, and CSS with 200+ lint rules and 97% Prettier compatibility. By parsing code once instead of twice (once for linting, once for formatting), Biome achieves significant speed improvements over the traditional ESLint + Prettier setup.

Biome targets JavaScript and TypeScript teams who want faster, simpler code quality tooling. It provides zero-config defaults, a VS Code extension, and built-in import sorting.

How it saves time or tokens

Biome processes files 25x faster than ESLint + Prettier combined because it runs in Rust and parses each file only once. The biome check --write command applies both formatting and lint fixes in a single pass. Zero-config defaults mean new projects get sensible rules immediately without configuring multiple tools.

How to use

1. Install Biome: npm install --save-dev --save-exact @biomejs/biome.
2. Initialize configuration: npx @biomejs/biome init (creates biome.json).
3. Run formatting and linting: npx biome check --write ..

Example

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

# Format all files
npx biome format --write .

# Lint all files
npx biome lint .

# Both at once
npx biome check --write .

Related on TokRepo

• AI Tools for Coding -- explore coding quality tools for JavaScript and TypeScript
• Automation Tools -- discover automated code quality workflows

Common pitfalls

• Biome does not yet support all ESLint plugins; check compatibility before migrating projects that rely on framework-specific rules like eslint-plugin-react-hooks.
• The 97% Prettier compatibility means 3% of edge cases format differently; run a diff comparison before committing to the migration.
• Biome's CSS support is newer and less mature than its JavaScript/TypeScript support; test CSS formatting thoroughly.