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coss ui

coss ui

Cal.com's Base UI + Tailwind v4 registry: 56 primitives and 500 particle variants

Tier A · StrongRegistryComponent LibraryBlock Collectionoriginui.com

(Visit originui.com ↗)(Docs)(Repository)(Registry)
Preview image from originui.com

coss ui is the successor to Origin UI — originui.com now serves it — and is the official design system Cal.com is progressively adopting. It ships 56 copy-paste React primitives built directly on Base UI (not ported from Radix) and styled with Tailwind v4, plus 500 'particles': pre-composed variants of those primitives such as 41 buttons, 25 calendars, 20 autocompletes and 20 badges. Everything installs through the shadcn CLI from its own registry, including a @coss/style preset that lays down colors, sidebar variables, fonts and base styles in one command. Origin UI itself remains online as a pre-acquisition collection with limited maintenance.

Install
pnpm dlx shadcn@latest add @coss/ui

For an agent

Use this when the project is on Base UI and Tailwind v4 and you want variants rather than bare primitives — the 500 particles are the real value, so instead of hand-building the 12th button style, pull p-button-N or p-calendar-N and edit. Initialize new projects with `pnpm dlx shadcn@latest init @coss/style` to get the tokens, sidebar variables and Inter/Geist Mono wiring in one shot; on an existing shadcn project add @coss/ui and @coss/colors-neutral separately so you keep your own theme. Two cautions: it is self-declared early development on top of Base UI's own beta, so pin what you copy; and the repo is AGPL-3.0 except the apps/origin and apps/ui directories, which matters if you vendor anything beyond the component files.

Why it is here. A 500-variant registry maintained as a real company's production design system is rare — most shadcn registries are one-person variant dumps, and this one ships with the migration path off Radix that the ecosystem is about to need.

Install command, framework, licence and component list.

Facts

License
MIT, AGPL
Pricing
Free, Open source
Framework
React, Next.js
Styling
Tailwind CSS v4, CSS custom properties
Distribution
shadcn registry, CLI installer, Copy-paste snippet, GitHub repository
Platform
Web
Content type
Code, Design tokens / theme files
Agent readiness
Machine-readable registry item, CLI installable, llms.txt, Copy-paste ready code, Structured documentation, Readable open source
Accessibility
Built on accessible primitives, Keyboard navigable, Focus management and visible focus
Maturity
Beta
GitHub stars
10,420

Components it ships

56 total
AccordionAlertAlert DialogAutocompleteAvatarBadgeBreadcrumbsButtonCalendarCardCheckboxCheckbox GroupCollapsibleComboboxCommand PaletteContext MenuDate PickerDialogDrawerEmpty StateFormFieldsetInput GroupText InputKbdLabelDropdown MenuMenubarMeterNumber InputOtp InputPaginationPopoverHover CardProgress BarRadio GroupScroll AreaSelectSeparatorSheetSkeletonSliderSpinnerSwitchTableTabsTextareaToastToggle ButtonToggle GroupToolbarTooltipPanelValidation MessageTheme ProviderDirection Provider

Helps you build

8
Settings Web AppSubmitting A FormShowing Input ErrorFiltering ItemsMulti Step FormSearch ResultsAdmin PanelAccount Web App

Notable for

  • 500 particle variants over 56 primitives
  • built natively on Base UI, not ported from Radix
  • official Cal.com design system
  • one-command @coss/style theme preset
  • Origin UI's successor at the same domain

Provenance

Verified 2026-08-15. HTTP 200. https://originui.com/, https://originui.com/particles, https://coss.com/ui/docs, https://coss.com/ui/docs/get-started, https://coss.com/ui/r/registry.json, https://github.com/origin-space/originui (301 -> cosscom/coss), https://api.github.com/repos/cosscom/coss

Also in Component Libraries

6
originui.comTier A