Why this API?

TanStack Query’s contract for a queryFn is simple. Most HTTP clients fight it.

TanStack Query needs	tanstack-fetch does
queryFn returns data	api.get<T>(path) → Promise<T>
Failures must throw	HTTP errors throw FetchError
Cancellation	Pass { signal } from queryFn
Typed errors	isFetchError(error) → status, code, body

Designed around Query

useQuery({
  queryKey: ['users'],
  queryFn: ({ signal }) => api.get<User[]>('/users', { signal }),
})

No wrapping if (!res.ok) — success returns data, failure throws FetchError.

Tiny by default

Import only what you need. The HTTP core is 3.57KB gzip. SSE, WebSocket / WebTransport / NDJSON (tanstack-fetch/live), React, Vue, plugins, and tRPC are separate entries.

Realtime on the same client

api.ws, api.transport and api.stream reuse your getToken, refresh-token and interceptors, and they reconnect with a fresh token. There's no second socket library to wire auth into. See WebSocket, WebTransport & streams.

First-class status handling

createFetch({
  interceptors: [
    createAuthInterceptor({ getToken: () => localStorage.getItem('access_token') }),
    createStatusInterceptor({
      401: () => logout(),
      403: () => toast.error('Forbidden'),
      404: () => toast.error('Missing'),
      '5xx': ({ status }) => console.error(status),
    }),
  ],
})

On tanstack-fetch/sse, /live and framework providers these are plain options: getToken, onUnauthorized, onForbidden, onNotFound, onServerError.

Handlers run before the error is thrown — Query still sees isError / FetchError.