Caching and Background Updates with React Query

In most web applications, the same data is often fetched multiple times — for example, when users revisit a page, switch between tabs, or interact with components that rely on the same resource. Without a caching mechanism, each interaction triggers a fresh network request, wasting bandwidth and slowing down the interface.

Traditional approaches using fetch or Axios don’t handle this automatically. Developers often resort to manually storing data in global state or local storage to avoid unnecessary calls — a workaround that quickly grows messy and unreliable.

How React Query solves it

React Query changes this by introducing a built-in caching layer. Once data is fetched, it’s automatically stored in memory and instantly reused when requested again. Even better, React Query keeps the cache synchronized with the server — re-fetching data in the background when needed, such as when the browser tab regains focus or after a configurable “stale” period.

This means our app always feels fast and fresh without us writing any extra code for caching, synchronization, or refetching logic.

React Query uses the queryKey as a unique identifier for each cached query. ...