Performance

Biome is written in Rust and processes files in parallel, making it 20-100x faster than ESLint on large codebases. A project with 10,000 TypeScript files that takes ESLint 45 seconds to lint finishes in under 1 second with Biome. This difference is transformative for CI pipelines and developer experience. ESLint 9 improved performance with flat config, but the architecture limits further gains.

// Biome vs ESLint comparison

// Speed (linting 1000 files):
// Biome:  ~50ms  (Rust-based, single binary)
// ESLint: ~2000ms (Node.js, plugin loading)

// Configuration:
// Biome: single biome.json — linter + formatter
// ESLint: .eslintrc + .prettierrc + eslint-config-prettier

// Rule coverage (as of 2026):
// Biome: ~300 rules (eslint, typescript-eslint, jsx-a11y)
// ESLint: ~600+ rules with plugins

// Biome advantages:
// ✅ 40x faster than ESLint
// ✅ Built-in formatter (replaces Prettier)
// ✅ Zero config needed for most projects
// ✅ Single dependency

// ESLint advantages:
// ✅ Larger plugin ecosystem
// ✅ More custom rule options
// ✅ Mature community support

Rule coverage

ESLint has the largest rule ecosystem through plugins — thousands of rules across hundreds of plugins. Biome implements 200+ built-in rules covering core ESLint, TypeScript-ESLint, React, React Hooks, JSX-A11y, import, and Unicorn rules. Biome v2 added type-aware rules (previously only available in TypeScript-ESLint). For most projects, Biome covers 85-95% of the rules actually enabled.

Formatting

Biome includes a built-in formatter that is 97% compatible with Prettier output. This eliminates the need for Prettier, eslint-config-prettier, and the conflicts between linting and formatting. ESLint deprecated its built-in formatting rules and recommends using Prettier separately, adding configuration complexity.

Configuration

Biome uses a single biome.json file for linting, formatting, and import sorting. ESLint requires .eslintrc.* for linting, .prettierrc for formatting, and plugin configs for import sorting. ESLint 9 introduced flat config (eslint.config.js), which is simpler than the legacy format but still requires separate Prettier config.

Ecosystem and plugins

ESLint wins on ecosystem breadth — plugins exist for nearly every framework and pattern. Biome has no plugin system yet, but its built-in rules cover the most widely-used plugins. If you depend on niche ESLint plugins (eslint-plugin-testing-library, eslint-plugin-tailwindcss), you may need to keep ESLint for those specific rules.