Upstream COSS roadmap
coss ui is the evolution of Origin UI, an open-source collection of React and Tailwind components created by Pasquale Vitiello and Davide Pacilio. It was recently acquired by Cal.com and grown into a broader, more ambitious ecosystem, with Pasquale contributing directly to the development of the new UI.
Our goal is to bring together the best parts of Origin UI with a stronger foundation—Base UI primitives—so developers get not just components, but a layered system of primitives, particles, and atoms.
Origin UI
Origin UI offered a large collection of 600+ ready-to-use UI components. With the transition to coss ui:
- The existing Origin UI components will evolve into particles—higher-level UI patterns composed of Base UI primitives.
- The original Origin UI collection remains available on this page, so developers can continue to access it during the transition.
Current Status
- 50+ UI primitives already available, with more on the way.
- A growing set of particles, progressively expanding to match and surpass the current Origin UI collection.
What’s Next
- Expand the primitives set, ensuring full coverage of common UI needs.
- Add more particles, aligning with and eventually replacing the original Origin UI collection.
- Introduce atoms, API-enhanced components that bring external integrations out of the box.
Svelte port status
COSS for Svelte ports the primitives, particles, documentation, and registry items from the pinned COSS reference. Each implementation receives separate parity, accessibility, and Svelte-quality review before integration.
The first release targets the pinned primitive and particle catalog, the shadcn-svelte registry, and
agent-readable Markdown routes. It does not include atoms or the legacy Origin application. This
repository adapts source only from the MIT-designated COSS reference/apps/ui subtree.