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Custom header

The headers option can be customize in config when using withTRPC in nextjs or createClient in react.js.

headers can be both an object or a function. If it's a function it will gets called dynamically every http request.

import { AppType } from "next/dist/shared/lib/utils";
import { withTRPC } from "@trpc/next";
import { AppRouter } from "@/server/routers/app";

export let token: string;

const MyApp: AppType = ({ Component, pageProps }) => {
return <Component {...pageProps} />;

export default withTRPC<AppRouter>({
config({ ctx }) {
* Headers will be called on each request.
headers() {
return {
Authorization: token

Example with auth login

const loginMut = trpc.useMutation(['auth.login'], {
onSuccess({ accessToken }) {
token = accessToken;

The token can be whatever you want it to be. It's entirely up to you whether that's just a client-side variable that you update the value of on success or whether you store the token and pull it from local storage.