Astryx

Astryx is an open-source design system created by Meta, battle-tested over 8 years and used in more than 13,000 internal apps. It is built on React and StyleX, offering 150+ accessible components, brand-level theming, ready-to-use templates, and a CLI for scaffolding, theme generation, and codemods. Its standout feature is being ‘Agent Ready’ – it supports the Model Context Protocol (MCP) so AI coding agents can read documentation, scaffold projects, and customize themes programmatically, weaving human-agent collaboration directly into the UI workflow.

Pros: rich components validated at scale, zero external UI dependencies, deep customizability; the CLI and MCP integration make AI-assisted development natural for internal tools and back-office systems that need fast iteration.

Cons: teams must be comfortable with React and StyleX, and StyleX adds a learning curve; the project is in Beta, so documentation and long-term stability are still evolving; the agent-first design can add complexity for simple pages.

Ideal for teams using React who want to empower AI coding agents while building internal tools or enterprise applications.