Next.js API Routes vs NestJS for Solo Developers

Quick Comparison

Next.js API Routes Overview

Next.js API Routes are the quickest way to add backend logic when you're already building with Next.js. Create a file in app/api/, export a function, deploy. No separate server process, no CORS configuration, no additional deployment pipeline.

I've shipped a few projects this way and the speed is real. For straightforward use cases like handling form submissions, proxying third-party APIs, or managing Stripe webhooks, API Routes keep everything in one place. You think in one codebase, deploy to one target, and debug in one set of logs.

The trade-off becomes obvious when your API grows. There's no built-in structure for organizing business logic. No dependency injection, no middleware pipeline, no module system. When you have 5 endpoints, that's fine. When you have 50, you're essentially inventing your own framework inside Next.js. And at that point, you probably should have picked a real one.

NestJS Overview

NestJS is the Angular of backend frameworks. Decorators, modules, dependency injection, providers, guards, interceptors. It brings heavy structure to Node.js applications. If you've worked with Spring Boot or ASP.NET, NestJS will feel familiar.

The structure is both the strength and the weakness. For large applications with complex business logic, NestJS keeps things organized. Services handle business logic. Controllers handle HTTP. Modules group related functionality. Everything has a clear place.

But for a solo developer, that structure comes with significant overhead. You'll write more boilerplate per feature than with most alternatives. Creating a simple CRUD endpoint requires a controller, a service, DTOs, and a module. That's a lot of files for "save this to the database and return it." I found myself fighting the framework more than building features during the early stages of a project.

Key Differences

Architecture philosophy is the core divide. Next.js API Routes are minimal by design. Each file is an independent endpoint. NestJS enforces a modular architecture with dependency injection, decorators, and a clear separation of concerns. One prioritizes simplicity, the other prioritizes structure.

TypeScript experience differs. Both use TypeScript, but NestJS leans heavily into decorators and metadata. If you love decorators and type-driven architecture, NestJS feels powerful. If decorators annoy you, prepare for a lot of @Controller(), @Injectable(), @Get(), and @Body().

Testing support. NestJS has excellent built-in testing utilities. Dependency injection makes mocking straightforward. Next.js API Routes have no testing framework. You'll set up Jest or Vitest yourself and mock everything manually.

Deployment model. API Routes deploy as serverless functions on Vercel, which means cold starts and execution time limits. NestJS runs as a traditional server process, giving you persistent connections, WebSockets, and no cold starts. Different runtime models for different needs.

Middleware and guards. NestJS has a sophisticated middleware pipeline with guards, interceptors, and pipes for validation. Next.js has basic middleware that runs at the edge. For complex auth flows or request validation, NestJS gives you more tools.

When to Choose Next.js API Routes

• Your project is already Next.js and the backend is lightweight
• You have fewer than 15-20 API endpoints
• You want zero deployment complexity
• You'd rather move fast than architect perfectly
• You're building a frontend-heavy app where the API is secondary

When to Choose NestJS

• You're building a backend that will grow to 50+ endpoints
• You need WebSockets, microservices, or GraphQL with strong structure
• Your business logic is complex enough to benefit from dependency injection
• You want built-in testing utilities and clear separation of concerns
• You're comfortable with the Angular-style decorator approach

The Verdict

For solo developers, I'd actually hesitate to recommend NestJS unless your project genuinely needs that level of structure. The boilerplate overhead is real, and when you're building alone, every unnecessary file slows you down.

Next.js API Routes work great for simple backends. But when you outgrow them, I'd suggest looking at lighter alternatives like Hono or Express before jumping to NestJS. NestJS is excellent for teams, but the ceremony it requires can feel like overkill when there's only one person writing all the code.

If you specifically want a structured TypeScript backend and you have the discipline to work within NestJS's patterns, it will reward you at scale. Just know that "at scale" usually means 6+ months into a growing project, not day one.