Astryx
An open-source design system built on React and StyleX that ships accessible components, theming, and a CLI meant to be used the same way by people and AI coding assistants.
Astryx is a design system that grew inside Meta over several years before being released as open source. It provides more than 150 accessible components, brand-level theming with dark mode, ready-to-use page templates, and a CLI, distributed as pre-built CSS with typed React components.
Components are designed to be composed at any level rather than locked behind a single top-level API, and a component's full source can be ejected into a project to customize directly. Theming works through CSS custom property overrides, so a project can restyle Astryx without forking or wrapping its components, and styling can be overridden with Tailwind, CSS modules, or plain CSS regardless of the StyleX authoring underneath.
It requires React 19 or later and is written in TypeScript under the MIT license.