Great backend APIs are not only about request and response handling. They are about reliability, clarity, and long-term maintainability.
Start with the contract
Before implementation, define the request payload, response shape, error format, authorization rules, and edge cases.
Think about production early
A production API should include validation, logging, tracing, metrics, rate limiting, pagination, and safe retry behavior.
Keep business logic clean
Controllers should stay thin. Put business logic into services, isolate database access, and keep external integrations behind clear interfaces.