Why Route Handlers?

Next.js App Router introduced route handlers as a modern replacement for API routes. They offer better performance, simpler patterns, and native support for streaming responses.

Getting Started

A route handler is simply a route.ts file inside any directory under app/:

export async function GET(request: Request) {
  const data = await fetchFromDatabase();
  return Response.json(data);
}

Best Practices

Use Proper HTTP Methods

Each route handler can export functions for different HTTP methods: GET, POST, PUT, PATCH, DELETE.

Validate Input

Always validate request bodies before processing. Use libraries like Zod for type-safe validation.

Handle Errors Gracefully

Return appropriate status codes and structured error messages. Never expose internal errors to clients.

Stream Large Responses

For large datasets, use streaming responses to reduce time-to-first-byte and improve perceived performance.

Performance Tips

Use Response.json() instead of NextResponse.json() for simpler cases
Implement caching headers for frequently accessed data
Use database connection pooling to avoid connection overhead
Consider edge runtime for latency-sensitive endpoints

Conclusion

Route handlers in Next.js provide a clean, powerful way to build APIs. By following these best practices, you can create APIs that scale with your application's growth.

Building Scalable APIs with Next.js Route Handlers