Valtio
Proxy-based state management library for React by Poimandres (pmndrs — also behind Zustand, Jotai, React-Spring). Valtio makes JavaScript objects reactive using Proxy — mutate state like plain JavaScript objects, and React components auto-subscribe to changes. Very little boilerplate — create a store with proxy(), mutate it directly, and useSnapshot() in components for reactive access. Mental model closest to MobX but lighter and proxy-based.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
MIT open source from pmndrs. Client-side only, no network calls. No credentials required. Standard web security applies.
⚡ Reliability
Best When
You want minimal-boilerplate React state management with an intuitive mutation model — especially for small-to-medium applications where Redux-style complexity is overkill.
Avoid When
You need strict action traceability, time-travel debugging with a clear action history, or complex state machines — use Redux Toolkit or XState.
Use Cases
- • Manage shared React state with minimal boilerplate using Valtio's mutable proxy model — no actions, reducers, or selectors needed
- • Share state between React components using Valtio stores that update automatically when mutated anywhere
- • Build agent configuration panels where state updates from multiple sources (user input, API responses) are reflected reactively
- • Use Valtio outside React components for shared mutable state that can also subscribe callbacks (subscribe())
- • Mix mutable state logic (direct property assignment) with React's immutable rendering model using Valtio's snapshot mechanism
Not For
- • Redux-style predictable state flows where all mutations go through explicit actions — Valtio's direct mutation model loses action traceability
- • Large applications needing strict state discipline — Zustand or XState offer more structured patterns for complex state
- • Non-React applications — Valtio can work standalone but is primarily designed for React
Interface
Authentication
Pure JavaScript library — no auth required. Client-side state management only.
Pricing
MIT open source from pmndrs community. Free forever.
Agent Metadata
Known Gotchas
- ⚠ Valtio uses JavaScript Proxy — state must not be frozen (Object.freeze()) or use non-configurable properties; both break Proxy interception
- ⚠ useSnapshot() returns an immutable snapshot — attempting to mutate the snapshot throws a frozen object error; mutations must happen on the proxy state, not the snapshot
- ⚠ Arrays in Valtio state are proxied — array methods (push, splice, sort) work correctly, but assigning a new array reference replaces the proxy; use splice/push for in-place mutations
- ⚠ Valtio state is mutable — concurrent mutations from multiple async operations can cause race conditions without explicit ordering; use useTransition or queue mutations for safety
- ⚠ DevTools integration requires valtio/utils devtools() wrapper — without it, state mutations are invisible in React DevTools
- ⚠ Deeply nested proxy state has overhead — very deep nesting (5+ levels) creates many nested Proxy objects; flatten state structure for performance-critical paths
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for Valtio.
Scores are editorial opinions as of 2026-03-06.