haydenbleasel/ultracite

Ultracite

The linter and formatter for agentic development.

Ultracite helps you and your AI models write consistent, type-safe code without the hassle of configuration. Pick your preferred toolchain, run one command, and get hundreds of battle-tested rules wired up in seconds — across single repos and monorepos alike.

For the thinking behind Ultracite, read The agentic development loop by Hayden Bleasel. For the reasoning behind the rules, browse our open research.

Quick Start

npx ultracite init

The interactive setup guides you through choosing your formatter/linter, framework, editor, and AI agents, then installs and configures everything for you. Re-run it any time to adjust your setup.

Prefer a different package manager? Ultracite detects yours automatically, or you can run it with pnpm dlx, yarn dlx, or bunx.

Commands

check and fix accept an optional list of files or globs; omit them to run against the whole project. Add -v / --version or -h / --help for CLI details.

fix also accepts --claude or --codex to hand any remaining unfixable issues to the Claude Code or Codex CLI, which repairs them autonomously file by file — each fix verified by a re-lint before it's marked done.

Common init flags for non-interactive / CI use:

See the CLI reference for the full, current list of options.

Supported Tools

• Biome — All-in-one formatting and linting in a single fast binary.
• ESLint + Prettier + Stylelint — The most mature ecosystem with the largest plugin support.
• Oxlint + Oxfmt — Rust-based tooling that runs dramatically faster than ESLint, part of the Oxc ecosystem.

Key Features

⚡ Subsecond Performance

Built around Rust-based tooling for near-instant analysis. On-save checks feel seamless and stay out of your way.

🎯 Zero-Config by Design

Hundreds of preconfigured rules tuned for modern JavaScript and TypeScript. It works out of the box, and you can override anything when you need to.

🤖 AI-Ready

Generate ruleset and context files for a wide range of AI agents — Claude Code, GitHub Copilot, Cursor, Gemini, and many more — so humans and models share one consistent style.

🏗️ Monorepo Ready

One unified toolchain configuration across every package and app, eliminating duplicate config files while keeping standards consistent.

Using the presets directly

Beyond the CLI, Ultracite publishes ready-made config presets you can extend in your own setup (Biome, ESLint, Oxlint, Oxfmt, Prettier, and Stylelint). ultracite init wires these up for you; if you'd rather reference them by hand, the configuration docs list the exact import paths and extension points for each toolchain.

Documentation

Full setup guides, configuration options, rule references, framework and editor integrations, and examples live in the docs:

• Website: https://www.ultracite.ai/
• Issues & discussions: https://github.com/haydenbleasel/ultracite

License

MIT © Hayden Bleasel