Kookie UI is a design-system to build consistent and scalable user interfaces.

An open-source fork of Radix Themes, focused on building scalable, consistent UI components with a fresh visual style and practical foundations.

Kookie UI

"Components like Shell in Kookie UI are a game changer for building responsive layouts. Getting responsiveness right is so difficult otherwise — Kookie UI has significantly reduced the UI load on our team."

AnujSoftware Engineer at Womp

Articles about Kookie UI

Announcements

Building on Radix: Card

Card in Kookie UI extends Radix Themes with two new variants, a material system for translucent effects, and props for edge-to-edge content. Same foundation, more flexibility.

January 9, 2026

New Component: Shell, a Layout Engine for Modern Apps

Shell is a declarative layout engine for application chrome. Seven layout slots, responsive presentation modes, state management, and resize with persistence—all without building layout infrastructure from scratch.

January 7, 2026

New Component: Introducing Chatbar in KookieUI

A composable, accessible chat input component that handles the complex parts of building AI chat interfaces while staying out of your way.

November 8, 2025

Articles

Designers owning the experience in production with KookieUI

Why Designers Should Own the Experience in Production

Why the design layer should live in code, how we do it with KookieUI at Womp, and what changes day to day.

November 12, 2025

KookieUI design system forked from Radix Themes with different design opinions

Kookie User Interface: Building my own Design System

KookieUI is a fork of Radix Themes with different design opinions. Same infrastructure, different choices about how a design system should work.

September 25, 2025

Who's Kookie? The Lore Behind the Name

All my projects are named after my dog Kookie. This is the lore my partner and I have created for her — the legend of Queen Lukita the Benevolent.

September 25, 2023