Building Typesafe APIs with tRPC

What is tRPC?

tRPC is a TypeScript framework for building APIs that focuses on type safety, validation, and ease of use. It enables developers to define endpoints and automatically generate type-safe clients for consuming those endpoints. Its features include automatic request validation, response serialization, and strong typing throughout the API lifecycle.

Setting Up a tRPC Project

To get started with tRPC, you'll need Node.js and npm or yarn installed on your machine. Begin by creating a new TypeScript project:

mkdir trpc-api
cd trpc-api
npm init -y
# or
yarn init -y

Next, install tRPC and its peer dependencies:

npm install trpc @trpc/server @trpc/client @trpc/client/next
# or
yarn add trpc @trpc/server @trpc/client @trpc/client/next

Defining Your API

Now, let's define a simple API using tRPC. Create a folder named api and add an endpoint to it. For example, let's create a helloWorld.ts file:

// api/helloWorld.ts

import { createTRPC } from '@trpc/server'
import { z } from 'zod'

const appRouter = createTRPC<{}>({
    router: {
        helloWorld: {
            input: null,
            resolve: () => {
                return { message: 'Hello, World!' }

export type Context = typeof appRouter extends infer Router
    ? Router extends createTRPC<infer Context>
        ? Context
        : never
    : never

export default appRouter

This endpoint helloWorld takes no input and simply returns a greeting message.

Creating the Server

Now, let's create the server to serve our API. Create an index.ts file in the root folder of your project:

// index.ts

import { createNextApiHandler } from '@trpc/server/adapters/next'
import { createContext } from './api/context'
import apiRouter from './api/helloWorld'

export default createNextApiHandler({
    router: apiRouter,

Running the Server

To start the server, run the following command:

npx next dev
# or
yarn dev

This will start the server, and your tRPC API will be available at http://localhost:3000/api/helloWorld.

Consuming the API

To consume the API, let's create a simple Next.js page. Create a file named index.tsx inside the pages directory:

// pages/index.tsx

import { GetServerSideProps } from 'next'
import { createReactQueryHooks } from '@trpc/react'
import { trpc } from '../utils/trpc'
import React from 'react'

const trpcClient = trpc.createClient()

const Home: React.FC = () => {
    const { data } = createReactQueryHooks(trpcClient).useQuery(['helloWorld'])

    return (
            <h1>tRPC Example</h1>

export default Home

export const getServerSideProps: GetServerSideProps = async () => {
    return {
        props: {},

This page uses @trpc/react and createReactQueryHooks to fetch the helloWorld endpoint data and display the message.


tRPC simplifies the process of creating APIs in TypeScript by providing type safety, automatic validation, and a straightforward API definition. It's a powerful tool for building robust and type-safe APIs.

This guide covered the basic setup and creation of a simple tRPC API. Explore more features and advanced usage to leverage the full potential of tRPC in your projects!