In the evolving landscape of web development, TypeScript has emerged as a cornerstone for building robust and scalable applications. Its type system provides a layer of safety that JavaScript lacks, catching errors at compile time that would otherwise only surface at runtime. While TypeScript is widely recognized for its benefits on the frontend, particularly with frameworks like Angular and React, its application on the backend is equally potent but less discussed. This article dives deep into creating type-safe backend APIs using TypeScript with tRPC, a modern framework that maximizes TypeScript’s capabilities to ensure type safety across client-server interactions.

Understanding tRPC and Its Ecosystem

tRPC stands for TypeScript Remote Procedure Call. Unlike traditional REST or GraphQL APIs, tRPC doesn't require you to manually define types for your requests and responses or write additional schemas. It allows you to create APIs that are fully type-safe by default, leveraging TypeScript’s advanced type inference to synchronize types across the frontend and backend seamlessly.

tRPC is built on top of frameworks like Express, Fastify, or Next.js, and it abstracts away the API layer, letting developers focus on writing the actual server and client logic without worrying about the type mismatches that often occur in network communication.

Setting Up a tRPC Project with TypeScript

To start, you’ll need Node.js installed on your machine. Let’s create a new Node.js project and configure it to work with TypeScript and tRPC. First, initialize a new node project:

mkdir trpc-example

cd trpc-example

npm init -y

npm install typescript ts-node @trpc/server @trpc/client express zod

Here, typescript is our core language tool, ts-node allows us to run TypeScript directly in Node without pre-compilation, @trpc/server and @trpc/client are the main tRPC libraries for the server and client-side, express is the web server framework, and zod is used for validation.

Next, set up TypeScript:

npx tsc --init

Modify the generated tsconfig.json to suit a Node.js environment by setting:

Create a basic Express server in a new src/index.ts file:

import express from 'express';

import * as trpcExpress from '@trpc/server/adapters/express';


const app = express();

const port = 3000;


app.get('/', (req, res) => {

res.send('Hello World!'); });


app.listen(port, () => {

console.log(`Server running at http://localhost:${port}`); });

Building Your First tRPC API

Let's add tRPC to our project. Define a simple procedure and integrate it with the Express server:

1. Define tRPC Procedures

Create a new file src/trpc.ts:

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

import { z } from 'zod';


const t = initTRPC.create();


const appRouter = t.router({

hello: t.procedure.input(z.string().optional()).query(({ input }) => {

return `Hello, ${input ?? 'world'}`; }), });


export type AppRouter = typeof appRouter;

export default appRouter;

2. Integrate tRPC with Express

Modify src/index.ts to use tRPC:

import express from 'express';

import * as trpcExpress from '@trpc/server/adapters/express';

import appRouter from './trpc';


const app = express();

const port = 3000;


app.use('/trpc', trpcExpress.createExpressMiddleware({

router: appRouter,

createContext: () => null, // Optional: add auth or other context here }));


app.listen(port, () => {

console.log(`Server running with tRPC at http://localhost:${port}`); });

Real-World Insights and Best Practices

When implementing tRPC in a production environment, consider the following best practices:

• Validation and Error Handling: Use Zod or similar libraries to validate input data rigorously. tRPC’s integration with Zod enhances type safety and helps prevent many common data-related issues.
• Context and Authentication: Utilize the createContext function wisely to pass necessary context or authentication details. This keeps your procedures clean and secure.
• Testing: Given the type-safe nature of tRPC, many typical API testing challenges (like type mismatches) are mitigated. However, always write end-to-end tests to ensure your API behaves as expected under different conditions.

By adopting tRPC for your TypeScript backend projects, you not only leverage TypeScript’s full potential but also simplify your development process, reduce runtime errors, and increase the maintainability of your applications. As TypeScript continues to evolve and tools like tRPC mature, the landscape of backend development is shifting towards complete, end-to-end type safety, making now an exciting time to invest in learning and implementing these powerful technologies.