Which one should I pick for a new project?

That depends entirely on what you're building:

pmndrs/valtio is for state management in React and vanilla JavaScript applications. Pick this if you need:

• A lightweight proxy-based state solution
• Render-optimized React components (only re-renders when accessed state changes)
• Simple, intuitive mutations without boilerplate
• A small bundle size

The architecture is very healthy (Grade A, 0 import cycles), with zero security vulnerabilities and clean code quality. It's production-ready for state management.

redwoodjs/redwood is a full-stack JavaScript/TypeScript framework for building web applications. Pick this if you need:

• An opinionated, integrated development experience
• Built-in API and web side with routing, authentication, and database integration
• Scaffolding and conventions that get you building quickly
• Server-side rendering, middleware authentication, caching layers

These solve different problems: Valtio is a state library, while Redwood is an application framework. You could actually use both together—Valtio for managing UI state within a Redwood project.

For a new project:

• Use Valtio alone if you're building a client-side app, widget, or state layer for existing infrastructure
• Use Redwood if you're building a complete full-stack web application from scratch and want conventions/tooling built in
• Use both if you're using Redwood and want its state management (you could use Valtio instead of Redux)

FOLLOW_UPS:

• What type of application are you building?
• Do you need a backend/API, or client-side only?
• Are you familiar with React or other frameworks?