Impeccable

Impeccable is a design add-on, called a skill, for AI coding assistants like Claude Code, Cursor and Codex. A skill is a set of instructions and small tools that your assistant follows while it works. Impeccable teaches your assistant design rules for type, colour, spacing, layout and motion, and gives you plain commands to steer it.

It's made by Paul Bakaus, and it grew out of Anthropic's own frontend design skill. It has almost 100,000 stars on GitHub.

What it can do

• Steer the design in plain words. Commands like bolder, quieter, colorize, typeset and layout change one thing at a time.
• Review your pages. Critique gives a scored design and usability review, and audit checks technical quality.
• Finish a page properly. Polish, harden and adapt tidy details, handle edge cases and fit other screen sizes.
• Spot generic AI design. A built-in detector flags patterns that make a page look machine-made.
• Remember your brand. Its setup step writes down your audience and brand once, and every later command reads it.
• Works with many assistants. Claude Code, Cursor, Codex, GitHub Copilot, Gemini CLI, OpenCode and many more.

What we found when we tested it

We gave Impeccable, the anti-slop skill and plain Claude the same brief for a small bakery website. With a full design system in the brief, all three pages looked much the same. Without one, Impeccable made a bold, poster-style page in blue and yellow with stencil lettering, while plain Claude made a typical cream and brown page with cards. It also had the highest text contrast of the three. It took about three minutes and 60 to 70% more tokens than plain Claude.

Impeccable, anti-slop or a DESIGN.md file?

All three help your AI assistant make better-looking pages. They differ in how much they decide for you.

IImpeccableThis page

Best forA distinctive look, and reviews of a site you already have

Has design opinions and commands to steer them. Slower and uses more tokens.

How you use it

Commands inside your AI assistant

Open source

Yes (Apache 2.0)

Cost

Free

Aanti-slop

Best forRemoving AI habits without imposing a style

A rulebook that filters out generic AI design and copy, and checks the page before it's done. Gives no direction of its own.

How you use it

Loads automatically in your AI assistant

Open source

Yes (MIT)

Cost

Free

DESIGN.md file

Best forA consistent brand you choose yourself

One file that sets your colours, fonts and spacing. Cheapest and fastest, but you choose the look.

How you use it

A file in your project folder

Open source

Yes (MIT, for design-bites)

Cost

Free

A quick way to choose: know the look you want? Write a DESIGN.md. Want your assistant to have design ideas of its own, or a review of an existing site? Use Impeccable. Want AI habits removed and nothing else? Use anti-slop.

How to get it

• You need Node.js and an AI coding assistant that works with files on your computer.
• Install it from your project folder with npx impeccable install, then reload your assistant.
• Set it up once by running /impeccable init in your assistant, which asks about your audience and brand. In Codex, start commands with $ instead of /.
• Use it by pointing a command at part of your page, like /impeccable critique the pricing cards.

Good to know

• It takes longer and uses more tokens than working without it, because it reads detailed design rules and checks its own work. In our test it was about three minutes instead of 33 seconds.
• It asks questions about your product and brand. Answer them, because they shape everything it does.
• When you start a new design, it fetches design directions from impeccable.style. It also records which direction you picked, unless you run npx impeccable telemetry off. Your project files and code aren't sent.
• To scan a live page, it needs Chrome or Edge.
• Licence: Apache 2.0. Free to use, change and include in products you sell, as long as you keep the licence and notices. Two reference files come from an MIT-licensed project and keep that licence.