Open source. Open possibilities.

Panda is a universal, type-safe CSS-in-JS framework for design systems. It extracts styles at build time, outputs modern CSS with cascade layers and variables, supports recipes and variants, and works with most JS frameworks.

Priceline Design System is Priceline.com's open-source UI component library and design standard. It aims to unify interface patterns, speed design and development, and promote accessibility, internationalization, and responsive web design. It ships as the npm package pcln-design-system with Storybook docs and an MIT license.

Chakra UI is an open-source React component system for building accessible web apps and SaaS products quickly. It ships installable component packages, supports Next.js RSC, and is MIT licensed.

Twin.macro is a Babel macro that brings Tailwind CSS utility classes to CSS-in-JS workflows, converting tw, css, styled, and theme usages into CSS objects at build time. It supports emotion, styled-components, solid-styled-components, stitches, and goober, with setup examples for Vite, Next.js, Gatsby, Storybook, and more.

styled-components is a CSS-in-JS library for React: write real CSS that is scoped automatically and delivered only when needed. One API covers server components, client components, streaming SSR and React Native; TypeScript types are built in, it is under 13kB gzipped and needs no build plugin.