The fetch index exports a map of route paths to their generated clients:

pages/example/index.tsx

import fetchClients from "_/fetch";

const response = await fetchClients["users/[id]"].GET([123]);

Method Signatures

Each client exposes methods for the HTTP verbs your route handles. The signature reflects your route definition directly:

• First argument is a parameter array, in path order
• Second argument is the payload, if your handler defines one

Given this route:

api/users/[id]/index.ts

export default defineRoute<"users/[id]", [number]>(({ GET }) => [
  GET<{
    query: { name?: string },
    response: [200, "json", { id: number; name: string; email: string }],
  }>(async (ctx) => { /* ... */ }),
]);

The generated client expects a number parameter and an optional payload:

pages/example/index.tsx

const useFetch = fetchClients["users/[id]"];

const response = await useFetch.GET([123]);
const response = await useFetch.GET([123], { query: { name: "John" } });
// response is typed as { id: number; name: string; email: string }

Routes Without Parameters or Payloads

No parameters, no array:

const response = await fetchClients["users"].GET();

If there is a payload to send without params, just use an empty array for params:

const response = await fetchClients["users"].GET([], {
  query: { filter: "active", page: 1 }
});

If the route defines no payload type (or never), the second argument is not required. The client adapts to exactly what your API expects - passing the wrong shape is a type error.

Isomorphic Fetch

The same call works in CSR and SSR without changes. In the browser it issues a same-origin network request; during SSR it dispatches to the API route in-process - the API server is bundled into the SSR bundle, so there's no network hop, just a direct call through the full middleware/validation/handler chain.

pages/example/index.tsx

// identical in a client component and in an SSR loader
const response = await fetchClients["users/[id]"].GET([123]);

Nothing to configure - no separate server-side client, no base URL for the in-process path. The path/href utilities still produce URL strings for links and external references (see Path Utilities); it's the request methods (GET, POST, ...) that swap transport on the server.