API Development Best Practices with NestJS

Design for Modularity

NestJS encourages modular architecture. Organize features into dedicated modules that encapsulate controllers, providers, and data access logic.

Validation and DTOs

Use class-validator and class-transformer to validate incoming payloads. DTOs provide a single source of truth for API contracts.

export class CreateArticleDto {
  @IsString()
  title!: string;

  @IsString()
  body!: string;

  @IsOptional()
  @IsArray()
  tags?: string[];
}

Error Handling

Implement global filters to translate thrown exceptions into consistent responses. NestJS ships with HttpException helpers, but custom filters keep the surface area predictable.

Authentication Strategies

Combine Passport strategies, JWT tokens, and Guards to protect sensitive routes. Pair them with policy-based authorization for fine-grained control.

Testing

NestJS integrates seamlessly with Jest. Use the TestingModule builder to instantiate modules in isolation and write repeatable integration tests.

Conclusion

With a clear module structure, rigorous validation, and thoughtful testing, NestJS helps you build APIs that are both maintainable and delightful to work with.