Getting Started with NestJS: A Beginner-Friendly Tutorial

NestJS is a progressive Node.js framework for building efficient and scalable server-side applications. Think of it as a backend version of Angular—structured, modular, and powerful.

If you know some basic JavaScript or TypeScript and you're comfortable with Node.js/Express, NestJS will feel like a well-organized upgrade.

🧰 Prerequisites

Before starting, make sure you have:

• Node.js (v16 or above): https://nodejs.org

• npm or yarn

• Basic knowledge of JavaScript or TypeScript

• Familiarity with REST APIs and Express is a plus

📦 Step 1: Install the Nest CLI

The Nest CLI is the easiest way to generate a new project and components.

bashCopyEditnpm i -g @nestjs/cli

⚙️ Step 2: Create Your First Project

Generate a new NestJS project using the CLI:

bashCopyEditnest new my-first-nest-app

You’ll be asked to choose a package manager — choose npm or yarn.

Once the installation is done:

bashCopyEditcd my-first-nest-app
npm run start:dev

Open your browser and visit:
👉 http://localhost:3000

You should see:
Hello World!

🏗️ Step 3: Understand the Project Structure

NestJS uses modules, controllers, and services.

Here’s the core structure you’ll see:

lessCopyEditsrc/
├── app.controller.ts      // Handles incoming HTTP requests
├── app.service.ts         // Contains business logic
├── app.module.ts          // Root module where everything is wired up
main.ts                    // Entry point

🧱 Step 4: Create Your First Module

Let’s say you want to create a simple cats feature.

bashCopyEditnest generate module cats

This creates cats/cats.module.ts.

🎮 Step 5: Create a Controller and Service

bashCopyEditnest generate controller cats
nest generate service cats

This gives you:

arduinoCopyEditsrc/cats/
├── cats.controller.ts
├── cats.service.ts
├── cats.module.ts

Update cats.controller.ts to look like this:

tsCopyEditimport { Controller, Get } from '@nestjs/common';
import { CatsService } from './cats.service';

@Controller('cats')
export class CatsController {
  constructor(private catsService: CatsService) {}

  @Get()
  findAll() {
    return this.catsService.findAll();
  }
}

Update cats.service.ts:

tsCopyEditimport { Injectable } from '@nestjs/common';

@Injectable()
export class CatsService {
  private readonly cats = [{ name: 'Whiskers', age: 2 }];

  findAll() {
    return this.cats;
  }
}

Now go to:
👉 http://localhost:3000/cats
And you'll get a list of cats!

Add a POST Route

In cats.controller.ts:

tsCopyEditimport { Controller, Get, Post, Body } from '@nestjs/common';

@Controller('cats')
export class CatsController {
  constructor(private catsService: CatsService) {}

  @Get()
  findAll() {
    return this.catsService.findAll();
  }

  @Post()
  create(@Body() cat: { name: string; age: number }) {
    return this.catsService.create(cat);
  }
}

In cats.service.ts:

tsCopyEditcreate(cat: { name: string; age: number }) {
  this.cats.push(cat);
  return { message: 'Cat added', cat };
}

Use Postman or curl:

bashCopyEditcurl -X POST http://localhost:3000/cats \
-H "Content-Type: application/json" \
-d '{"name": "Tiger", "age": 3}'

What Next?

• Explore DTOs and Validation with @nestjs/class-validator

• Connect a database using @nestjs/typeorm or @nestjs/mongoose

• Use Guards, Pipes, and Interceptors for advanced use cases

• Add authentication with Passport and JWT

Resources

• Official docs: https://docs.nestjs.com

• CLI docs: https://docs.nestjs.com/cli/overview

• Example projects: https://github.com/nestjs/nest

Recap

NestJS gives you a full toolbox to write clean, testable, and enterprise-grade APIs with Node.js. You’ve just built your first NestJS app with a custom controller, service, and route!

Keep building from here—NestJS is massive, but beginner-friendly with the right steps.

Getting started

main.ts (engine startup/entry point)

app.module.ts = main module/root module: specifies imports, controllers and providers (services)