Free · MIT · open source

Fable Design System

Free, open-source design taste for AI coding agents.

The Fable Design System is a free, MIT-licensed design skill for AI coding agents — Claude Code, Cursor, Codex, and Antigravity. Install it and your agent designs like an award-winning SaaS designer instead of shipping the same generic Tailwind template every AI defaults to.

Get it on GitHub — free How to install

Install in one command

Auto-detects Claude, Codex, and Antigravity/Gemini and installs the skill into each. No sudo, nothing runs in the background.

curl -fsSL https://raw.githubusercontent.com/ajantoniou/fable-design-system/main/install.sh | bash

Restart your agent and ask it to build a page. Prefer to read it first? It's open source — inspect install.sh in the repo.

See it on four real, shipping products

Each pair is the same brand and the same copy — left is a default AI agent's output, right is the identical page rebuilt with the Fable Design System. These aren't mockups; the "after" matches four real sites in production.

UploadCheck landing page: default AI output vs the same page with the Fable Design System
UploadCheck — pre-publish media QC
HealthBrew landing page: default AI output vs the same page with the Fable Design System
HealthBrew — daily health reflection
EstimateProof landing page: default AI output vs the same page with the Fable Design System
EstimateProof — used-car deal check
Cliros landing page: default AI output vs the same page with the Fable Design System
Cliros — real-estate closing automation

The "before" pages are real, un-coached output from a fast model given a plain "build a landing page" prompt — not strawmen.

Why AI-generated UI all looks the same

The default-template problem

Most AI agents ship gray Inter on flat white, purple gradients, and identical rounded cards — because they improvise instead of declaring a design system.

A design brain, not a kit

Fable is a set of operating instructions plus concrete tokens that change how your agent thinks about design — type, color, spacing, motion, and self-critique.

Real before/after proof

The repo shows the same brand and copy built by a default agent vs. with Fable installed, across four real shipping products — not mockups.

Frequently asked questions

Is it really free?

Yes — completely free and open-source under the MIT license. No paywall, no account, no sign-up.

Which agents work?

Claude Code, Cursor, Codex, and Antigravity/Gemini. The installer auto-detects what you have.

Is it a component library?

No. It changes how the agent thinks about design rather than giving it parts to assemble.

Where's the spec?

The full design persona and tokens live in the open-source repo (FABLE-DESIGN-PERSONA.md).