Code Formatting Tools Compared: Prettier vs ESLint vs Biome
Consistent code formatting eliminates style debates and reduces diff noise in code reviews. Prettier, ESLint, and Biome take different approaches to formatting and linting. This comparison helps you choose the right tool.
Key Takeaways
- Code formatting debates (tabs vs spaces, semicolons vs no semicolons, trailing commas) consume disproportionate review time.
- Prettier is an opinionated formatter for JavaScript, TypeScript, CSS, HTML, JSON, Markdown, and more.
- ESLint is primarily a linter (code quality checker) for JavaScript/TypeScript, but with plugins like `eslint-plugin-prettier` or its built-in formatting rules, it can also enforce formatting.
- Biome (formerly Rome) is a Rust-based all-in-one tool that combines formatting and linting in a single binary.
Why Consistent Formatting Matters
Code formatting debates (tabs vs spaces, semicolons vs no semicolons, trailing commas) consume disproportionate review time. An automated formatter ends these debates permanently: the tool decides, everyone follows, and code reviews focus on logic instead of style.
Prettier
Prettier is an opinionated formatter for JavaScript, TypeScript, CSS, HTML, JSON, Markdown, and more. Its key philosophy: minimal configuration. Prettier makes most formatting decisions for you, offering fewer than 20 options.
Strengths:
- Broad language support (JS, TS, CSS, HTML, JSON, MD, YAML, GraphQL)
- Truly opinionated — minimal configuration debates
- Excellent IDE integration
- Industry standard for JavaScript/TypeScript projects
Weaknesses:
- Formatter only — does not catch code quality issues (unused variables, bugs)
- Some formatting decisions are controversial and non-configurable
- Performance can be slow on large codebases (Node.js-based)
ESLint
ESLint is primarily a linter (code quality checker) for JavaScript/TypeScript, but with plugins like eslint-plugin-prettier or its built-in formatting rules, it can also enforce formatting. ESLint 9's flat config simplified configuration.
Strengths:
- Code quality rules beyond formatting (no-unused-vars, no-undef, complexity)
- Highly configurable — hundreds of rules, each independently toggleable
- Auto-fix capability for many issues
- Massive plugin ecosystem
Weaknesses:
- Configuration complexity (config files can grow to hundreds of lines)
- Formatting rules conflict with Prettier if both are used
- Slower than dedicated formatters for pure formatting tasks
- JavaScript/TypeScript only (no CSS, HTML, Markdown)
Biome
Biome (formerly Rome) is a Rust-based all-in-one tool that combines formatting and linting in a single binary. It's dramatically faster than Prettier and ESLint because it's compiled, not interpreted.
Strengths:
- 10-100x faster than Prettier + ESLint combined
- Single tool for both formatting and linting
- Zero-config defaults that match Prettier's output
- No Node.js dependency (standalone Rust binary)
Weaknesses:
- Smaller plugin ecosystem than ESLint
- Language support still growing (JS, TS, JSON, CSS — no HTML, MD, YAML yet)
- Fewer lint rules than ESLint
Recommendation
| Scenario | Recommended |
|---|---|
| New JS/TS project | Biome (fastest, simplest) |
| Existing project with ESLint | Keep ESLint, add Prettier for formatting |
| Multi-language (JS + CSS + MD) | Prettier (broadest language support) |
| Maximum lint coverage | ESLint + Prettier |
| Performance-critical CI | Biome (10-100x faster) |