Why migrate to Biome?

Biome is 20-100x faster than ESLint because it is written in Rust and processes files in parallel. It combines linting, formatting, and import sorting in a single tool, eliminating the need for Prettier, eslint-config-prettier, and eslint-plugin-import. A single biome.json replaces .eslintrc, .prettierrc, and .editorconfig. Biome v2 added type-aware linting, closing the last major gap with TypeScript-ESLint.

// Migrate from ESLint + Prettier to Biome

// 1. Install Biome
npm install --save-dev --save-exact @biomejs/biome
npx @biomejs/biome init

// 2. biome.json — equivalent of .eslintrc + .prettierrc
{
  "linter": {
    "enabled": true,
    "rules": { "recommended": true }
  },
  "formatter": {
    "enabled": true,
    "indentStyle": "space",
    "indentWidth": 2
  }
}

// 3. Update package.json scripts
// "lint": "biome check ."        (replaces eslint .)
// "format": "biome format --write ."  (replaces prettier --write .)

// 4. Remove old deps
// npm uninstall eslint prettier eslint-config-prettier

Step 1: Generate biome.json

Use the converter above to paste your .eslintrc.json and generate a biome.json. Review the warnings tab for rules that have no Biome equivalent — you may need to accept slightly different behavior or add Biome-specific rules. Save the output as biome.json in your project root.

Step 2: Install and run Biome

Install Biome as a dev dependency: npm install --save-dev --save-exact @biomejs/biome. Run npx biome check --write . to lint and format your entire codebase. Review the changes, then commit. The --write flag auto-fixes all fixable issues.

Step 3: Remove ESLint and Prettier

Uninstall ESLint, Prettier, and all related plugins: npm uninstall eslint prettier eslint-config-prettier @typescript-eslint/eslint-plugin @typescript-eslint/parser eslint-plugin-react eslint-plugin-import. Delete .eslintrc.*, .prettierrc, .prettierignore, and .eslintignore. Update package.json scripts to use biome check instead of eslint and prettier.

Step 4: Update CI/CD and editors

Replace ESLint and Prettier steps in your CI pipeline with npx biome ci . (the ci command fails on any issue, unlike check). Install the Biome VS Code extension (biomejs.biome) and disable the ESLint and Prettier extensions. Configure format-on-save to use Biome. For JetBrains IDEs, install the Biome plugin from the marketplace.