tanstack-fetch 2.0.0: a 3.57KB core and typed params on every live call

October 31, 2026

2.0.0 is about paying only for what you use, and about types that hold all the way to the socket:

• Slim core: tanstack-fetch goes from 5.14KB to 3.57KB gzip. Auth, status handlers and plugins are interceptors you add
• Typed live params: api.sse, api.ws, api.transport, api.stream, useSse and useWs type params like api.get
• NDJSON fixes: streamed request bodies on Node, onRequestError on network failures, abortable retry delays

Upgrade

npm install tanstack-fetch@2.0.0

Two breaking changes, both caught by TypeScript. If you import createFetch from tanstack-fetch/sse or /live, pass options to createTRPCFetch (/trpc), or configure a framework provider, only the second one can affect you.

At a glance

Import	Before	2.0.0
tanstack-fetch	5.14KB	3.57KB
tanstack-fetch/sse	6.29KB	6.33KB
tanstack-fetch/live	8.60KB	8.75KB
tanstack-fetch/trpc	3.16KB	3.28KB

1. The core is interceptors only

Core createFetch keeps baseUrl, headers, source, incoming, timeoutMs, interceptors, fetch, credentials and maxRetries. Everything else is an interceptor from tanstack-fetch/plugins, which you already had:

import { createFetch } from 'tanstack-fetch'
import {
  createAuthInterceptor,
  createRetryIdempotentInterceptor,
  createStatusInterceptor,
  createTraceInterceptor,
} from 'tanstack-fetch/plugins'

export const api = createFetch({
  baseUrl: 'https://api.example.com',
  interceptors: [
    createAuthInterceptor({ getToken: () => localStorage.getItem('access_token') }),
    createStatusInterceptor({
      401: () => logout(),
      '5xx': ({ status }) => toast.error(`Server error ${status}`),
    }),
    createTraceInterceptor(),
    createRetryIdempotentInterceptor(),
  ],
})

1.x option on core createFetch	2.0.0
getToken / auth	createAuthInterceptor({ getToken })
onUnauthorized, onForbidden…	createStatusInterceptor({ 401: fn, 403: fn })
onClientError / onServerError	createStatusInterceptor({ '4xx': fn, '5xx': fn })
onStatus: map	createStatusInterceptor(map)
plugins: ['trace', …]	createTraceInterceptor(), …
api.upload(), progress events	createFetch from tanstack-fetch/sse

The shortcuts did not go away: tanstack-fetch/sse, /live, /trpc and every framework provider still accept them, together with upload() and progress events. The fastest upgrade is one line:

- import { createFetch } from 'tanstack-fetch'
+ import { createFetch } from 'tanstack-fetch/sse'

npx tanstack-fetch migrate now scaffolds the interceptor style.

2. Typed params on every live call

Live calls used to lose params typing the moment you passed a message type, because TypeScript stops inferring the path literal. They now take a params type in the same position as api.get<Data, Params>:

// Inferred from the URL: `id` required
api.ws('/rooms/:id', { params: { id: 7 } })

// Your types: message, params, outgoing frames
const room = api.ws<ChatMessage, { id: number }, OutgoingMessage>('/rooms/:id', {
  params: { id: 7 },
})

api.sse<OrderEvent, { id: string }>('/orders/:id/events', { params: { id }, onMessage })
for await (const chunk of api.stream<Token, { id: string }>('/chat/:id', { params: { id } })) {
  render(chunk)
}

// @ts-expect-error the path has no :id
api.ws<ChatMessage, { id: number }>('/rooms/:roomId', { params: { id: 7 } })

The hooks follow suit in React, Vue, Solid, Svelte and Angular:

const { data, send } = useWs<ChatMessage, { id: string }, OutgoingMessage>('/rooms/:id', {
  params: { id: roomId },
  authIn: 'query',
})

Generic order is <Message, Params, Send> for ws / transport / useWs, and <Message, Params> for sse / stream / useSse. Use NoParams to skip to Send. tanstack-fetch generate now emits the params type for SSE and NDJSON operations too.

Also fixed

• api.stream() with a ReadableStream body sends duplex: 'half', which Node / undici require.
• Network errors in api.stream() run onRequestError (retry, short-circuit) like HTTP calls.
• Aborting during a retry delay rejects right away instead of waiting the delay out.

Upgrade notes

1. Core createFetch from tanstack-fetch with getToken, plugins, status shortcuts or upload(): move them to interceptors, or switch the import to tanstack-fetch/sse.
2. ws / transport / useWs with two generics: ws<Message, Send> is now ws<Message, Params, Send> — insert your params type or NoParams.

See also: Plugins · WebSocket, WebTransport & streams · Changelog