Next.js API routes allow adding server-side code directly to Next.js projects, supporting both simple apps and large-scale products.API files are placed under /pages/api for file-based routing and run as serverless functions, handling requests and responses separately.Next.js API routes simplify organization with file-based routing and automatic serverless deployment on platforms like Vercel or Netlify.Benefits of Next.js API routes include serverless deployment, unified frontend and backend, easy scaling, rapid prototyping, and easy updates.