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Installation​

tRPC is split between several packages, so you can install only what you need. Make sure to install the packages you want in the proper sections of your codebase. For this quickstart guide we'll keep it simple and use the vanilla client only. For framework guides, check out usage with React and usage with Next.js.

Requirements

Start off by installing the @trpc/server and @trpc/client packages:

npm install @trpc/server @trpc/client

AI Agents

If you use an AI coding agent, install tRPC skills for better code generation:

bash

npx @tanstack/intent@latest install

Your first tRPC API​

Let's walk through the steps of building a typesafe API with tRPC. To start, this API will contain three endpoints with these TypeScript signatures:

ts

type User = { id: string; name: string; };

userList: () => User[];

userById: (id: string) => User;

userCreate: (data: { name: string }) => User;

Here's the file structure we'll be building. We recommend separating tRPC initialization, router definition, and server setup into distinct files to prevent cyclic dependencies:

.

├── server/

│ ├── trpc.ts # tRPC instantiation & setup

│ ├── appRouter.ts # Your API logic and type export

│ └── index.ts # HTTP server

└── client/

`└── index.ts       # tRPC client`

1. Create a router instance​

First, let's initialize the tRPC backend. It's good convention to do this in a separate file and export reusable helper functions instead of the entire tRPC object.

server/trpc.ts

ts

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

/**

* Initialization of tRPC backend

* Should be done only once per backend!

*/

const t = initTRPC.create();

/**

* Export reusable router and procedure helpers

* that can be used throughout the router

*/

export const router = t.router;

export const publicProcedure = t.procedure;

Next, we'll initialize our main router instance, commonly referred to as appRouter, to which we'll later add procedures. Lastly, we need to export the type of the router which we'll later use on the client side.

server/appRouter.ts

ts

import { router } from './trpc';

export const appRouter = router({

// ...

});

export type AppRouter = typeof appRouter;

2. Add a query procedure​

Use publicProcedure.query() to add a query procedure to the router.

The following creates a query procedure called userList that returns a list of users:

server/appRouter.ts

ts

import { publicProcedure, router } from './trpc';

export const appRouter = router({

userList: publicProcedure

`.query(async () => {`

  `const users: User[] = [{ id: '1', name: 'Katt' }];`

  `return users;`

`}),`

});

export type AppRouter = typeof appRouter;

3. Using input parser to validate procedure inputs​

To implement the userById procedure, we need to accept input from the client. tRPC lets you define input parsers to validate and parse the input. You can define your own input parser or use a validation library of your choice, like zod, yup, or superstruct.

You define your input parser on publicProcedure.input(), which can then be accessed on the resolver function as shown below:

The input parser can be any ZodType, e.g. z.string() or z.object().

server/appRouter.ts

ts

import { publicProcedure, router } from './trpc';

import { z } from 'zod';

export const appRouter = router({

// ...

userById: publicProcedure

`.input(z.string())`

`.query(async (opts) => {`

  `const { input } = opts;`

           `const input: string`

  `const user: User = { id: input, name: 'Katt' };`

  `return user;`

`}),`

});

export type AppRouter = typeof appRouter;

server/appRouter.ts

ts

import { publicProcedure, router } from './trpc';

import { z } from 'zod';

export const appRouter = router({

// ...

userById: publicProcedure

`.input(z.string())`

`.query(async (opts) => {`

  `const { input } = opts;`

           `const input: string`

  `const user: User = { id: input, name: 'Katt' };`

  `return user;`

`}),`

});

export type AppRouter = typeof appRouter;

4. Adding a mutation procedure​

Similar to GraphQL, tRPC makes a distinction between Query and Mutation procedures.

The distinction between a Query and a Mutation is primarily semantic. Queries use HTTP GET and are intended for read operations, while Mutations use HTTP POST and are intended for operations that cause side effects.

Let's add a userCreate mutation by adding it as a new property on our router object:

server/appRouter.ts

ts

import { publicProcedure, router } from './trpc';

export const appRouter = router({

// ...

userCreate: publicProcedure

`.input(z.object({ name: z.string() }))`

`.mutation(async (opts) => {`

  `const { input } = opts;`

           `const input: {     name: string; }`

  `// Create the user in your DB`

  `const user: User = { id: '1', ...input };`

  `return user;`

`}),`

});

export type AppRouter = typeof appRouter;

Serving the API​

Now that we have defined our router, we can serve it. tRPC has first-class adapters for many popular web servers. To keep it simple, we'll use the standalone Node.js adapter here.

server/index.ts

ts

import { createHTTPServer } from '@trpc/server/adapters/standalone';

import { appRouter } from './appRouter';

const server = createHTTPServer({

router: appRouter,

});

server.listen(3000);

See the full backend code

Using your new backend on the client​

Let's now move to the client-side code and embrace the power of end-to-end typesafety. When we import the AppRouter type for the client to use, we have achieved full typesafety for our system without leaking any implementation details to the client.

1. Setup the tRPC Client​

client/index.ts

ts

import { createTRPCClient, httpBatchLink } from '@trpc/client';

import type { AppRouter } from './appRouter';

// 👆 **type-only** imports are stripped at build time

// Pass AppRouter as a type parameter. 👇 This lets `trpc` know

// what procedures are available on the server and their input/output types.

const trpc = createTRPCClient<AppRouter>({

links: [

`httpBatchLink({`

  `url: 'http://localhost:3000',`

`}),`

],

});

Links in tRPC are similar to links in GraphQL, they let us control the data flow to the server. In the example above, we use the httpBatchLink, which automatically batches up multiple calls into a single HTTP request. For more in-depth usage of links, see the links documentation.

2. Type Inference & Autocomplete​

You now have access to your API procedures on the trpc object. Try it out!

client/index.ts

ts

// Inferred types

const user = await trpc.userById.query('1');

   `const user: User`

const createdUser = await trpc.userCreate.mutate({ name: 'Katt' });

      `const createdUser: User`

You can also use your autocomplete to explore the API on your client

client/index.ts

ts

trpc.u;

Next steps​

What's next?

Description

Example Apps

Explore tRPC in your chosen framework

TanStack React Query

Recommended React integration via @trpc/tanstack-react-query

Next.js

Usage with Next.js

Server Adapters

Express, Fastify, and more

Transformers

Use superjson to retain complex types like Date