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SSR and browser APIs

Which hooks are SSR-safe and which should only run after mount.

SSR-safe hooks#

Pure state and effect helpers such as useToggle, useBoolean, useCounter, useSetState, usePrevious, useMemoizedFn, and useRequest are safe to import during SSR.

Browser-only hooks#

Hooks that rely on window, document, storage, observers, fullscreen, drag and drop, or WebSocket APIs should render only after mount. This site wraps those demos in BrowserOnly so the static build stays safe.

Examples include:

  • useLocalStorageState
  • useSessionStorageState
  • useCookieState
  • useUrlState
  • useTheme
  • useResponsive
  • useInViewport
  • useVirtualList
  • useWebSocket

Practical rule#

If a hook touches a browser global in its implementation or needs a DOM target, treat it as client-only in SSR and SSG applications.