Ultracite (haydenbleasel): a Claude skill that sets up and runs the Ultracite linter and formatter

The Ultracite skill makes Claude set up, run and follow the Ultracite linting and formatting rules in JavaScript and TypeScript projects.

Installs: 12.3K; on skills.sh
Stars: 3.4K; on GitHub
Files: 5; besides SKILL.md
Updated: Nov 2026; last repo commit

Claude uses this skill when a project has Ultracite, or when you ask to lint, format, set up Ultracite or fix lint errors. It checks package.json and your config files to see which linter you use: Oxlint, Biome, or ESLint with Prettier and Stylelint. Then it runs the ultracite commands check, fix, doctor, init and upgrade with your package manager.

It also tells Claude the project's code standards when it writes or reviews code. These cover type safety, modern JavaScript, async handling, React accessibility and security. The skill needs the ultracite package in your project and bundles no scripts. It has four upgrade guides, for versions 5 to 8.

Good for

JavaScript and TypeScript developers who use or want to adopt Ultracite
Teams moving an ESLint, Prettier or Biome setup onto Ultracite presets
Developers who want their AI agent to follow the same lint rules their CI checks

Install ultracite

Claude Code

Copy this prompt.

Install the ultracite skill in Claude Code. Run this command:

npx ultracite init --install-skill

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Requires Node.js, A JavaScript or TypeScript project.

Run the first command inside your project. It sets up Ultracite and then installs the skill, because the skill only drives the ultracite command in your project. Use the skills CLI command only if the project already uses Ultracite. The init command is interactive unless you pass --yes.

From the project README. Source.

What's in the skill

When it loads

Ultracite is a zero-config linting and formatting preset for JavaScript/TypeScript projects. Use when: (1) Setting up or initializing Ultracite in a project, or migrating its existing lint and format config onto Ultracite (ultracite init), (2) Running linting or formatting commands (check, fix, doctor), (3) Writing or reviewing JS/TS code in a project that uses Ultracite — to follow its code standards, (4) Troubleshooting linting/formatting issues, (5) Upgrading Ultracite or bringing its configuration up to a newer release (ultracite upgrade), (6) User mentions 'ultracite', 'lint', 'format', 'code quality', or 'biome/eslint/oxlint' in a project with Ultracite installed.

Sections in SKILL.md

Detecting Ultracite
CLI Commands
Initialization
Migrating an Existing Project
Upgrading
Code Standards
Troubleshooting

Key facts

Author: haydenbleasel (GitHub)
Repo: haydenbleasel/ultracite (skills/ultracite)
License: MIT
Installs on skills.sh: 12,345 as of 2026-11-02
GitHub stars: 3,367 (whole repo) as of 2026-11-02
Last repo commit: 2026-11-01
Folder contents: 6 files including SKILL.md: a code standards guide and four upgrade guides (v5 to v8) in references/
Needs: The ultracite npm package in your project, run with bun, npm, pnpm or yarn
skills.sh audits: Gen Agent Trust Hub pass, Socket pass, Snyk pass

What it includes

Reads package.json and config files to find the linter in use.
Files · Detect Ultracite
Lints without writing changes, for the whole project or given files.
Runs code · check
Lints and auto-fixes files, and can hand leftovers to an agent CLI.
Runs code · fix
Checks the linter install, config, dependency and conflicting tools.
Runs code · doctor
Sets up Ultracite, with flags for linter, editors, agents, frameworks and hooks.
Runs code · init
Moves existing ESLint, Prettier, Biome or Oxlint config onto Ultracite presets.
Runs code · Migrate a project
Installs the latest Ultracite and reinstalls the linter at supported versions.
Runs code · upgrade
Four guides, v5 to v8, for older configs.
Files · Upgrade guides
Rules for Claude when it writes JS or TS in an Ultracite project.
Code standards

From the official docs

Permissions

Medium risk

Claude runs package manager commands in your project that install dependencies and rewrite files. Commit your work first, and review the diff after init, fix or upgrade.

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

It installs dependencies and rewrites files
`init` installs packages and writes config, editor and agent files. `fix` edits source files. Use a clean git branch so you can review and undo.
`upgrade` downloads the latest release
SKILL.md says `upgrade` installs the latest Ultracite and reinstalls the linter. With `--claude` or `--codex` it has that agent CLI apply upgrade guides.
Hooks can run auto-fix on your edits
The `--hooks` option for `init` enables auto-fix hooks for Claude, Codex, Copilot, Cursor and others. Only enable it if you want fixes applied automatically.
`init --yes` skips the prompts
`--yes` takes the defaults without asking, and SKILL.md says it applies automatically when `CI=true` or there is no terminal. The default linter is Oxlint when you do not pass `--linter`. Run `init` interactively the first time.

Questions

What does the Ultracite skill do?

It teaches Claude to work with Ultracite, a zero-config linting and formatting preset for JavaScript and TypeScript. Claude can set it up, migrate an existing ESLint, Prettier or Biome config, run checks and fixes, diagnose problems, and upgrade between versions.

How do I install it?

Use the install box above. The first command sets up Ultracite in your project and installs the skill in one go. The skills CLI command installs only the skill, which helps when Ultracite is already in the project.

Does it need an API key?

No key is mentioned. It runs the ultracite command in your project through bun, npm, pnpm or yarn.

Which linters does it support?

Three: Oxlint with Oxfmt (the recommended default), Biome, and ESLint with Prettier and Stylelint. It finds the one you use from your config files.

Is it safe?

It runs commands in your project that change files. init installs dependencies and writes config files, fix rewrites code, and upgrade installs the latest Ultracite. Commit your work first so you can review the diff, and read the flags before you approve an init --yes run.

What does the hand-off flag do?

The CLI README says fix --claude or fix --codex hands issues it cannot fix to the Claude Code or Codex CLI, which repairs them file by file and re-lints each fix. Treat it as an agent making code edits.

Does it work in Codex or Cursor?

SKILL.md says init supports 40 agents and many editors, and can add auto-fix hooks for Claude, Codex, Copilot, Cursor and others. Use the install box for the skill itself; the --agents and --editors flags configure each tool.

Information

updated Nov 2, 2026

Repository: haydenbleasel/ultracite
Folder: skills/ultracite

haydenbleasel/ultracite skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 3

Ultracite CLI README · github.com
ultracite SKILL.md · github.com
ultracite on skills.sh · skills.sh