Designing Scalable APIs with NestJS

When building production-ready APIs, moving beyond the basics of request/response cycles is crucial. In this post, I explore how to structure a NestJS application for long-term maintainability.

Hexagonal Architecture

Separating your domain logic from the framework implementation details is step one. By using Ports and Adapters, we ensure our business rules aren't tightly coupled to HTTP controllers.

// Example of a domain service interface
export interface IUserService {
  create(user: User): Promise<User>;
  findById(id: string): Promise<User | null>;
}

Validation Pipes

Never trust client input. Using class-validator and global pipes ensures data integrity before it even reaches your business logic.