#3131st of 92 in SaaS and app starters
ui
React component library on Base UI and Tailwind, copied into your project
- Stars
- 10.8k
- License
- MIT
- Last commit
- Nov 2026
- Language
- TypeScript
9,419 on 22 Apr 202610,835 on 11 Nov 2026
From GitHub's daily star counts.
Checked on GitHub.
Overview
coss ui is the Cal.com design system: accessible React components built on Base UI primitives and styled with Tailwind CSS, distributed in the copy-and-own style of shadcn/ui. The repo is a Turborepo monorepo with the marketing site, the component docs (Fumadocs), and a legacy Radix-based Origin UI snapshot. It contains no AI features, so it fits this list only as a UI base for app starters.
Who it is for: React developers who want an accessible Base UI component set to build app UIs
Strengths
- Built on Base UI primitives, with Tailwind styling and TypeScript throughout
- Copy-and-own model: components live in your codebase, not behind a package API
- Used as the design system for cal.com, so it has a production consumer
- MIT license covers the whole repository, including the legacy Origin UI components
Weaknesses
- No AI, model or chat functionality; it is a UI kit only
- Origin UI components are a legacy snapshot with limited maintenance
- No tagged release; the repo has no versioned package releases
- Monorepo setup needs three .env.local files to make cross-app links work
What it needs
- TypeScript
- Needs Base UI, Tailwind CSS, Next.js, Bun, Turborepo
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