coss

coss.com/ui (formerly Origin UI) is described as the official design system of Cal.com. The repository is a monorepo containing several products and applications, all written in TypeScript and managed with Turborepo. Repository layout The monorepo lists these apps and packages: - apps/www/ — the main coss.com website - apps/ui/ — the coss ui component library and documentation - apps/origin/ — legacy Origin UI components, kept as a pre-acquisition snapshot - packages/ui/ — shared UI components package - packages/typescript-config/ — TypeScript configurations - biome.json — shared Biome configuration for linting and formatting Environment variables Because several Next.js applications link to one another, each app needs its own .env.local file so cross-app navigation works locally. The README documents variables for the www app (NEXT_PUBLIC_APP_URL, NEXT_PUBLIC_COSS_UI_URL), the ui app (NEXT_PUBLIC_APP_URL, NEXT_PUBLIC_COSS_URL, NEXT_PUBLIC_ORIGIN_URL) and the origin app (NEXT_PUBLIC_APP_URL, NEXT_PUBLIC_COSS_URL, NEXT_PUBLIC_COSS_UI_URL), with example localhost ports 3000, 4000 and 4001. Turborepo watches .env* files, so cache is invalidated when those variables change. Development workflow Tooling includes TypeScript for static type checking and Biome for linting and formatting. Commands are run with bun: `bun run build` and `bun run dev` build or start everything, while `--filter=www`, `--filter=ui` or `--filter=origin` target a single app. What coss ui provides coss ui is presented as a collection of accessible, composable React components built on top of Base UI and styled with Tailwind CSS, designed so that developers can copy, paste and own the code. The README states that Base UI's unstyled primitives are given a ready-to-use design system, and that this is the component library Cal.com plans to adopt progressively. Development continues in the open. Origin UI acquisition The repository includes the Origin UI components as a legacy snapshot: a Radix-based, shadcn-style collection that remains usable but with limited support and maintenance. Active work is said to focus on the new Particles components built on coss ui primitives. Contributions are invited via the guidelines in apps/ui/CONTRIBUTING.md, covering bug reports, features and documentation. Licensing Licensing is mixed. The default for the project is AGPLv3.0, while apps/origin/ and apps/ui/ remain under their original MIT license; all other directories fall under AGPLv3. Details are in LICENSING.md. Acknowledgements The README credits Tailwind CSS for the utility-first CSS framework, Base UI for the accessible primitives underlying the components, shadcn/ui for inspiring the copy-paste component philosophy, and Fumadocs for the documentation framework behind the component docs.