@coss

Reliable 91/100 · #13 of 342 scored

A new, modern UI component library built on top of Base UI. Built for developers and AI.

@coss is a shadcn UI community registry. Its source repository is cosscom/coss , which has 10.6k GitHub stars, 545 forks and 55 contributors. The last commit was 1d ago (29 commits in the last 90 days). It scores 91/100 on Sealambda's maturity index, placing it in the Reliable tier.

Scoring

Maturity breakdown

91 / 100 · Reliable

0avoid · 305080 · reliable100

monorepo confidence 100% · weight backed by data

Maintenance ×35% 90 → +31.4

last commit 2d ago · 29 commits/90d · solo maintainer

Popularity ×20% 100 → +20.0

10.6k★ · 545 forks

Community ×20% 83 → +16.6

55 contributors · bus factor 1 · 34 watching

Responsiveness ×13% 100 → +13.0

175/175 issues closed (100%)

Hygiene ×12% 85 → +10.2

AGPL-3.0 · 50% health files

Signals

Repository facts

10.6k
Stars: 545
Forks: 55
Contributors: 1
Bus factor: 0
Open issues: 175
Closed issues: 29
Commits (90d): TypeScript
Language: AGPL-3.0
License: —
Latest version: none
Releases: 1d ago
Last commit

Classification

License, pricing and purpose

License: AGPL-3.0 · ✓ OSI-approved; Network copyleft: Like strong copyleft, and offering the software over a network also counts as distribution.
Access: FOSS; An OSI-approved or FSF-libre license, and everything offered is free.
Purpose: Cal.com's official design system offering a complete suite of React UI components built on Base UI and Tailwind CSS.
Commercial model: Free; Everything the project offers is free to use, with no paid tier. Donations and sponsorships do not count as paid.
Tied to a service: No; Yes when the components are a client for a commercial API or service.
Scope: Complete kit; A broad, general-purpose component set that covers most everyday primitives (buttons, inputs, dialogs, menus, tables) and can be the main UI kit of an app, whether it restyles shadcn/ui or extends it.
Domains: Forms, Calendar & scheduling, Theming; Forms: Form controls beyond the basics: pickers, multi-selects, validation, form builders. Calendar & scheduling: Calendars, schedulers, date ranges and booking. Theming: Themes, color systems, fonts and theme generators.
Design: Themed; Keeps the shadcn/ui structure but ships its own tokens (colors, radius, fonts, shadows), so it reads as a branded variant.
Coverage: 68%; Share of shadcn/ui core primitives that the registry ships.
Design distance: 0.82; Measured on sample items: 0 is identical to vanilla shadcn/ui, 1 is entirely different.

Evidence

“© 2026 coss.com – open source, open heart, open mind.”
commercial · homepage ↗
“coss.com/ui is the official Cal.com Design System.”
scope · readme ↗
“coss ui is a collection of beautifully designed, accessible, and composable components for your React apps. Built on top of Base UI and styled with Tailwind CSS”
scope · readme ↗
“We've taken its powerful, unstyled primitives and given them a design system that's ready to go, right out of the box.”
design · readme ↗
“Calendar A date picker component with range and multi-select support.”
domains · homepage ↗
“Field A component that provides labelling and validation for form controls.”
domains · homepage ↗

AI-suggested by google/gemini-3.8-flash@Google on 2026-10-02

Usage

Install

Add components from this registry with the shadcn CLI (configure the registry URL in your components.json):

pnpm dlx shadcn@latest add @coss/[component]

endpoint: https://coss.com/ui/r/{name}.json

Homepage ↗ GitHub ↗

README

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[![shadcn maturity](https://shadcn.sealambda.com/badge/coss.svg)](https://shadcn.sealambda.com/registry/coss/)

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