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Server & Services

Where does your backend logic live in a Next.js application?

Server-side code in Next.js spans middleware, server actions, API routes, and background jobs. The boundary between "server component" and "service" keeps shifting — the constant is that business logic belongs in a domain layer, not scattered across route handlers.

Backend Code​

  • Middleware — Request interception: rewrites, redirects, headers, cookies
  • Durable Functions — Stateful workflows and long-running processes
  • Entities & DTOs — Domain layer separation from transport objects
  • Email — Transactional and marketing email services
  • GraphQL — Graph query layer integration
  • Headless CMS — Content management backends

Context​

Questions​

Where should the boundary sit between server components and dedicated API routes?

  • When does a server action become complex enough to extract into a service layer?
  • How do you test server-side logic without spinning up the full Next.js runtime?
  • What changes when background jobs need to survive deployment restarts?