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.

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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

Command	Description
`ultracite init`	Initialize Ultracite in the current directory (interactive by default).
`ultracite check [files...]`	Lint without writing changes. Unknown flags are passed through to the underlying linter.
`ultracite fix [files...]`	Lint and auto-fix. Unknown flags are passed through to the underlying linter.
`ultracite doctor`	Verify your Ultracite setup and diagnose configuration issues, including linter version mismatches.
`ultracite upgrade`	Update Ultracite and reinstall your linter toolchain at the versions it supports.

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:

Flag	Description
`--linter <linter>`	Toolchain to configure (Biome, ESLint, or Oxlint).
`--pm <pm>`	Package manager to use.
`--editors <editors...>`	Editors to configure (use `universal` for `.vscode/settings.json`).
`--agents <agents...>`	AI agents to enable (use `universal` for `AGENTS.md`).
`--frameworks <frameworks...>`	Frameworks in use, for framework-aware rules.
`--workspace-framework <path=framework...>`	Frameworks for one workspace of a monorepo (e.g. `apps/web=react`).
`--js-plugins <plugins...>`	Optional Oxlint JS plugins to enable (`@shadcn/lint`, `anti-slop`, `eslint-plugin-github`, `eslint-plugin-jsdoc`, `eslint-plugin-sonarjs`, `eslint-plugin-tsdoc`, `oxlint-plugin-react-doctor`).
`--type-aware`	Enable type-aware linting, and the `strictNullChecks` it needs.
`--install-skill`	Install the reusable Ultracite skill after setup.
`--skip-install`	Configure without installing dependencies.
`--yes`, `-y`	Take the defaults without prompting (automatic in CI and without a terminal).
`--quiet`	Only print warnings and errors.

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.