React Query (TanStack Query) is a library that manages server state, caching, and synchronization in React apps. Frontend engineers use it to eliminate boilerplate for data fetching, reduce loading states, and keep UI in sync with server. Learning time: 2–3 months. Salary impact: High; RQ is industry standard. Adjacent: React Advanced, REST APIs, State Management, Next.js.
React Query is a data-fetching and caching library for React that eliminates the complexity of managing server state. Instead of manually writing fetch-dispatch-setLoading-setError code, you declare what data you need, and React Query handles fetching, caching, background revalidation, and synchronization. The library uses a simple key-value cache backed by query keys. When you fetch the same data twice, React Query returns cached results instantly and revalidates in the background. It's especially powerful for apps with lots of API calls and shifting data states.
| Region | Junior | Mid | Senior |
|---|---|---|---|
| USA | $85k | $135k | $195k |
| UK | $50k | $85k | $130k |
| EU | $55k | $90k | $135k |
| CANADA | $80k | $130k | $185k |
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