Astryx

Overview

Astryx is an open-source, agent-ready design system and component library created by Meta. Designed to unify human developer workflows and AI assistant interactions, Astryx ships with 150+ accessible React components, brand-level CSS custom property theming, dark mode, and a CLI companion. It allows engineers and LLM coding agents to compose, customize, and inspect UI building blocks without forced component wrapping or top-level API lock-in. Built on React and StyleX, Astryx supports styling overrides using Tailwind CSS, CSS modules, or standard CSS.

What it does

• • Provides 150+ accessible React UI components with typed props and open internal compositions
• • Exposes a CLI companion that enables both human developers and AI coding agents to inspect docs, scaffold, and build themes
• • Supports token-level CSS custom property overrides to retheme applications without forking component source code
• • Integrates styling overrides seamlessly via classNames, Tailwind CSS, or CSS modules without build plugin requirements.

Who it's for

• Frontend Developers & React Engineers
• Product Designers & UI/UX Architects
• AI Software Agent Builders & LLM Developers
• Enterprise Software Development Teams

Why it works

• Agent-ready CLI and unified docs allow AI coding assistants to build UI components with the same precision as human engineers
• Open internals and swizzle capabilities enable developers to eject and customize full component source code when needed
• Token-based CSS custom property architecture provides deep retheming without forking or wrapping base components
• Free, open-source permissive licensing eliminates proprietary subscription costs and vendor lock-in risks.

Founder story

Astryx grew inside Meta over eight years as xDesign—the company's largest internal design system powering over 13,000 applications. Recognizing that traditional design systems force developers to choose between rigid, uncustomizable APIs or unmaintained copy-paste snippets, Meta's engineering team rebuilt the architecture on an open-source stack. Released publicly in 2026, Astryx was crafted to serve both human developers and the AI coding agents working alongside them.

Alternatives

• Shadcn UI
• Radix UI
• Chakra UI
• MUI

Comparison overview

• Astryx is built natively for AI coding agent interaction with a CLI docs interface and open component internals.
• Alternative libraries like MUI or Chakra UI lock styling logic behind closed top-level component props, making token-level retheming and AI agent inspection more complex.