COSS UI

Overview

coss ui is the official Cal.com design system, a modern React component library built on Base UI and published at coss.com/ui. It was formerly Origin UI, and the legacy Origin components still live in the same monorepo alongside the new library.

The registry contains 59 UI components and more than 500 numbered example blocks showing each component in different configurations. Components install with the shadcn CLI, and the whole set can be added at once. The project describes itself as built for developers and AI, and the codebase is 100% TypeScript in a Turborepo of Next.js apps.

Features

• Base UI foundation: Components are built on Base UI primitives rather than Radix.
• 59 components: Accordion, autocomplete, combobox, command, date picker, drawer, menu, meter, number field, OTP field, segmented control, sidebar, toast, toolbar and more.
• Chat and composer: Chat and composer components for AI-style interfaces.
• Example particles: Hundreds of ready-made variants, such as 40 button and 24 calendar examples, to copy as starting points.
• Forms: Field, fieldset, form, checkbox group, input group and textarea components, with Zod used in form examples.
• Data tables: Table examples built with TanStack Table.

Tech stack

• React, Base UI
• Tailwind CSS, shadcn CLI
• TypeScript, Next.js, Turborepo
• lucide-react, date-fns, TanStack Table

Registry

Install via the shadcn CLI registry:

npx shadcn@latest add @coss/component-name