Set up with Next.js App Router (v11)

Recommended file structure

.
├── src
│   ├── app
│   │   ├── api
│   │   │   └── trpc
│   │   │       └── [trpc]
│   │   │           └── route.ts  # <-- tRPC HTTP handler
│   │   ├── layout.tsx            # <-- mount TRPCReactProvider
│   │   └── page.tsx              # <-- server component
│   ├── trpc
│   │   ├── init.ts               # <-- tRPC server init & context
│   │   ├── routers
│   │   │   ├── _app.ts           # <-- main app router
│   │   │   ├── post.ts           # <-- sub routers
│   │   │   └── [..]
│   │   ├── client.tsx            # <-- client hooks & provider
│   │   ├── query-client.ts       # <-- shared QueryClient factory
│   │   └── server.tsx            # <-- server-side caller
│   └── [..]
└── [..]

Add tRPC to an existing Next.js App Router project

1. Install deps

pnpm add @trpc/server @trpc/client @trpc/tanstack-react-query @tanstack/react-query@latest zod client-only server-only

npm install @trpc/server @trpc/client @trpc/tanstack-react-query @tanstack/react-query@latest zod client-only server-only

yarn add @trpc/server @trpc/client @trpc/tanstack-react-query @tanstack/react-query@latest zod client-only server-only

bun add @trpc/server @trpc/client @trpc/tanstack-react-query @tanstack/react-query@latest zod client-only server-only

Initialize your tRPC backend in trpc/init.ts using the initTRPC function, and create your first router. We're going to make a simple "hello world" router and procedure here — for deeper information on creating your tRPC API, refer to the Quickstart guide and Backend usage docs.

trpc/init.ts

import { initTRPC } from '@trpc/server';

/**
 * This context creator accepts `headers` so it can be reused in both
 * the RSC server caller (where you pass `next/headers`) and the
 * API route handler (where you pass the request headers).
 */
export const createTRPCContext = async (opts: { headers: Headers }) => {
  // const user = await auth(opts.headers);
  return { userId: 'user_123' };
};

// Avoid exporting the entire t-object
// since it's not very descriptive.
// For instance, the use of a t variable
// is common in i18n libraries.
const t = initTRPC
  .context<Awaited<ReturnType<typeof createTRPCContext>>>()
  .create({
    /**
     * @see https://trpc.io/docs/server/data-transformers
     */
    // transformer: superjson,
  });

// Base router and procedure helpers
export const createTRPCRouter = t.router;
export const createCallerFactory = t.createCallerFactory;
export const baseProcedure = t.procedure;

trpc/routers/_app.ts

import { z } from 'zod';
import { baseProcedure, createTRPCRouter } from '../init';

export const appRouter = createTRPCRouter({
  hello: baseProcedure
    .input(
      z.object({
        text: z.string(),
      }),
    )
    .query((opts) => {
      return {
        greeting: `hello ${opts.input.text}`,
      };
    }),
});

// export type definition of API
export type AppRouter = typeof appRouter;

3. Create the API route handler

With the App Router, use the fetch adapter to handle tRPC requests. Create a route handler that exports both GET and POST:

app/api/trpc/[trpc]/route.ts

import { fetchRequestHandler } from '@trpc/server/adapters/fetch';
import { createTRPCContext } from './trpc/init';
import { appRouter } from './trpc/routers/_app';

const handler = (req: Request) =>
  fetchRequestHandler({
    endpoint: '/api/trpc',
    req,
    router: appRouter,
    createContext: () => createTRPCContext({ headers: req.headers }),
  });

export { handler as GET, handler as POST };

4. Create a Query Client factory

Create a shared file trpc/query-client.ts that exports a function that creates a QueryClient instance.

trpc/query-client.ts

import {
  defaultShouldDehydrateQuery,
  QueryClient,
} from '@tanstack/react-query';
import superjson from 'superjson';

export function makeQueryClient() {
  return new QueryClient({
    defaultOptions: {
      queries: {
        staleTime: 30 * 1000,
      },
      dehydrate: {
        // serializeData: superjson.serialize,
        shouldDehydrateQuery: (query) =>
          defaultShouldDehydrateQuery(query) ||
          query.state.status === 'pending',
      },
      hydrate: {
        // deserializeData: superjson.deserialize,
      },
    },
  });
}

We're setting a few default options here:

staleTime: With SSR, we usually want to set some default staleTime above 0 to avoid refetching immediately on the client.
shouldDehydrateQuery: This is a function that determines whether a query should be dehydrated or not. Since the RSC transport protocol supports hydrating promises over the network, we extend the defaultShouldDehydrateQuery function to also include queries that are still pending. This will allow us to start prefetching in a server component high up the tree, then consuming that promise in a client component further down.
serializeData and deserializeData (optional): If you set up a data transformer in the previous step, set this option to make sure the data is serialized correctly when hydrating the query client over the server-client boundary.

5. Create a tRPC client for Client Components

The trpc/client.tsx is the entrypoint when consuming your tRPC API from client components. In here, import the type definition of your tRPC router and create typesafe hooks using createTRPCContext. We'll also export our context provider from this file.

trpc/client.tsx

'use client';

// ^-- to make sure we can mount the Provider from a server component
import type { QueryClient } from '@tanstack/react-query';
import { QueryClientProvider } from '@tanstack/react-query';
import { createTRPCClient, httpBatchLink } from '@trpc/client';
import { createTRPCContext } from '@trpc/tanstack-react-query';
import { useState } from 'react';
import { makeQueryClient } from './query-client';
import type { AppRouter } from './routers/_app';

export const { TRPCProvider, useTRPC } = createTRPCContext<AppRouter>();

let browserQueryClient: QueryClient;
function getQueryClient() {
  if (typeof window === 'undefined') {
    // Server: always make a new query client
    return makeQueryClient();
  }
  // Browser: make a new query client if we don't already have one
  // This is very important, so we don't re-make a new client if React
  // suspends during the initial render. This may not be needed if we
  // have a suspense boundary BELOW the creation of the query client
  if (!browserQueryClient) browserQueryClient = makeQueryClient();
  return browserQueryClient;
}

function getUrl() {
  const base = (() => {
    if (typeof window !== 'undefined') return '';
    if (process.env.VERCEL_URL) return `https://${process.env.VERCEL_URL}`;
    return 'http://localhost:3000';
  })();
  return `${base}/api/trpc`;
}

export function TRPCReactProvider(
  props: Readonly<{
    children: React.ReactNode;
  }>,
) {
  // NOTE: Avoid useState when initializing the query client if you don't
  //       have a suspense boundary between this and the code that may
  //       suspend because React will throw away the client on the initial
  //       render if it suspends and there is no boundary
  const queryClient = getQueryClient();

  const [trpcClient] = useState(() =>
    createTRPCClient<AppRouter>({
      links: [
        httpBatchLink({
          // transformer: superjson, <-- if you use a data transformer
          url: getUrl(),
        }),
      ],
    }),
  );

  return (
    <QueryClientProvider client={queryClient}>
      <TRPCProvider trpcClient={trpcClient} queryClient={queryClient}>
        {props.children}
      </TRPCProvider>
    </QueryClientProvider>
  );
}

Mount the provider in the root layout of your application:

app/layout.tsx

import { TRPCReactProvider } from '~/trpc/client';

export default function RootLayout({
  children,
}: Readonly<{
  children: React.ReactNode;
}>) {
  return (
    <html lang="en">
      <body>
        <TRPCReactProvider>{children}</TRPCReactProvider>
      </body>
    </html>
  );
}

6. Create a tRPC caller for Server Components

To prefetch queries from server components, we create a proxy from our router. You can also pass in a client if your router is on a separate server.

trpc/server.tsx

import 'server-only'; // <-- ensure this file cannot be imported from the client

import { createTRPCOptionsProxy } from '@trpc/tanstack-react-query';
import { headers } from 'next/headers';
import { cache } from 'react';
import { createTRPCContext } from './init';
import { makeQueryClient } from './query-client';
import { appRouter } from './routers/_app';

// IMPORTANT: Create a stable getter for the query client that
//            will return the same client during the same request.
export const getQueryClient = cache(makeQueryClient);

export const trpc = createTRPCOptionsProxy({
  ctx: async () =>
    createTRPCContext({
      headers: await headers(),
    }),
  router: appRouter,
  queryClient: getQueryClient,
});

// If your router is on a separate server, pass a client instead:
// createTRPCOptionsProxy({
//   client: createTRPCClient({ links: [httpLink({ url: '...' })] }),
//   queryClient: getQueryClient,
// });

7. Make API requests

You're all set! You can now prefetch queries in server components and consume them in client components.

Prefetching in a Server Component

app/page.tsx

import { dehydrate, HydrationBoundary } from '@tanstack/react-query';
import { getQueryClient, trpc } from '~/trpc/server';
import { ClientGreeting } from './client-greeting';

export default async function Home() {
  const queryClient = getQueryClient();
  void queryClient.prefetchQuery(
    trpc.hello.queryOptions({
      text: 'world',
    }),
  );

  return (
    <HydrationBoundary state={dehydrate(queryClient)}>
      <ClientGreeting />
    </HydrationBoundary>
  );
}

Using data in a Client Component

app/client-greeting.tsx

'use client';

// <-- hooks can only be used in client components
import { useQuery } from '@tanstack/react-query';
import { useTRPC } from '~/trpc/client';

export function ClientGreeting() {
  const trpc = useTRPC();
  const greeting = useQuery(trpc.hello.queryOptions({ text: 'world' }));
  if (!greeting.data) return <div>Loading...</div>;
  return <div>{greeting.data.greeting}</div>;
}

Tip

You can create prefetch and HydrateClient helper functions to make this more concise:

trpc/server.tsx

export function HydrateClient(props: { children: React.ReactNode }) {
  const queryClient = getQueryClient();
  return (
    <HydrationBoundary state={dehydrate(queryClient)}>
      {props.children}
    </HydrationBoundary>
  );
}

export function prefetch<T extends ReturnType<TRPCQueryOptions<any>>>(
  queryOptions: T,
) {
  const queryClient = getQueryClient();
  if (queryOptions.queryKey[1]?.type === 'infinite') {
    void queryClient.prefetchInfiniteQuery(queryOptions as any);
  } else {
    void queryClient.prefetchQuery(queryOptions);
  }
}

Then you can use it like this:

import { HydrateClient, prefetch, trpc } from '~/trpc/server';
import { ClientGreeting } from './client-greeting';

function Home() {
  prefetch(trpc.hello.queryOptions({ text: 'world' }));

  return (
    <HydrateClient>
      <ClientGreeting />
    </HydrateClient>
  );
}

Leveraging Suspense

You may prefer handling loading and error states using Suspense and Error Boundaries. You can do this by using the useSuspenseQuery hook.

app/page.tsx

import { HydrateClient, prefetch, trpc } from '~/trpc/server';
import { Suspense } from 'react';
import { ErrorBoundary } from 'react-error-boundary';
import { ClientGreeting } from './client-greeting';

export default async function Home() {
  prefetch(trpc.hello.queryOptions());

  return (
    <HydrateClient>
      <ErrorBoundary fallback={<div>Something went wrong</div>}>
        <Suspense fallback={<div>Loading...</div>}>
          <ClientGreeting />
        </Suspense>
      </ErrorBoundary>
    </HydrateClient>
  );
}

app/client-greeting.tsx

'use client';

import { useSuspenseQuery } from '@tanstack/react-query';
import { useTRPC } from '~/trpc/client';

export function ClientGreeting() {
  const trpc = useTRPC();
  const { data } = useSuspenseQuery(trpc.hello.queryOptions());
  return <div>{data.greeting}</div>;
}

Getting data in a Server Component

If you need access to the data in a server component, we recommend creating a server caller and using it directly. Please note that this method is detached from your query client and does not store the data in the cache. This means that you cannot use the data in a server component and expect it to be available in the client. This is intentional and explained in more detail in the Advanced Server Rendering guide.

trpc/server.tsx

import { headers } from 'next/headers';
import { createTRPCContext } from './init';
import { appRouter } from './routers/_app';

// ...
export const caller = appRouter.createCaller(async () =>
  createTRPCContext({ headers: await headers() }),
);

app/page.tsx

import { caller } from '~/trpc/server';

export default async function Home() {
  const greeting = await caller.hello();

  return <div>{greeting.greeting}</div>;
}

If you really need to use the data both on the server as well as inside client components and understand the tradeoffs explained in the Advanced Server Rendering guide, you can use fetchQuery instead of prefetch to have the data both on the server as well as hydrating it down to the client:

app/page.tsx

import { getQueryClient, HydrateClient, trpc } from '~/trpc/server';
import { ClientGreeting } from './client-greeting';

export default async function Home() {
  const queryClient = getQueryClient();
  const greeting = await queryClient.fetchQuery(trpc.hello.queryOptions());

  // Do something with greeting on the server

  return (
    <HydrateClient>
      <ClientGreeting />
    </HydrateClient>
  );
}

Next steps

Learn about Server Actions for defining tRPC-powered server actions
Learn about queries and mutations in client components
Explore server-side calls for more advanced server-side patterns
Check out the SSE Chat example for a full App Router example with subscriptions

Set up with Next.js App Router

Recommended file structure

Add tRPC to an existing Next.js App Router project

1. Install deps

2. Create a tRPC router

3. Create the API route handler

4. Create a Query Client factory

5. Create a tRPC client for Client Components

6. Create a tRPC caller for Server Components

7. Make API requests

Prefetching in a Server Component

Using data in a Client Component

Leveraging Suspense

Getting data in a Server Component

Next steps

Pages under App Router