Programming Tutorials

  You have migrated an API endpoint to the Next.js App Router. It works perfectly in development ( next dev ). However, once you build and deploy to production, the endpoint behaves strangely. You update a record in your database, hit the endpoint to fetch the updated list, and receive the   old   data. No matter how many times you refresh, the data remains stale until you rebuild the application. This is not a bug in your database logic. It is a fundamental misunderstanding of how the App Router handles caching compared to the Pages Router. The Root Cause: Static by Default In the older Pages Router ( pages/api ), every API route was treated as a  Dynamic Serverless Function . It executed on every request. In the App Router ( app/api ), Next.js inverts this paradigm. Route Handlers are  Static by Default . When you run  next build , Next.js analyzes your Route Handlers. It will automatically cache the response of a  GET  handler at build time and...