Getting Started with NestJS: Your First API in TypeScript

NestJS brings Angular-style architecture — modules, dependency injection, decorators — to backend Node.js development. If you already know TypeScript, this is the most structured way to build a Node API without inventing your own conventions from scratch.

Installing and Creating a Project

npm i -g @nestjs/cli
nest new my-api
cd my-api
npm run start:dev

Generating a Resource

Nest's CLI scaffolds an entire CRUD module — controller, service, module, and DTOs — in one command:

nest generate resource posts

Controllers: Handling HTTP Requests

@Controller('posts')
export class PostsController {
  constructor(private postsService: PostsService) {}

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

  @Post()
  create(@Body() dto: CreatePostDto) {
    return this.postsService.create(dto);
  }
}

Notice the constructor: PostsService is injected, not manually instantiated. Nest's dependency injection container handles wiring it up.

DTOs and Validation

export class CreatePostDto {
  @IsString()
  @IsNotEmpty()
  title: string;

  @IsString()
  body: string;
}

With class-validator and a global ValidationPipe enabled, invalid requests are rejected automatically before they ever reach your controller method — no manual validation code needed.

Services: Where Business Logic Lives

@Injectable()
export class PostsService {
  private posts = [];

  findAll() {
    return this.posts;
  }

  create(dto: CreatePostDto) {
    const post = { id: Date.now(), ...dto };
    this.posts.push(post);
    return post;
  }
}

Controllers stay thin — they just delegate to services, the same "thin controller" principle from Laravel and every other mature framework.

Why Choose Nest Over Plain Express

Express gives you total freedom and zero structure — fine for a tiny script, painful once three developers are working on the same codebase with three different opinions about folder layout. Nest trades a bit of that freedom for consistency: every Nest project you'll ever open looks roughly the same, which matters enormously on a team.