Start with the data model
Define the resources, relationships and access rules before writing endpoint handlers. A useful API contract states the expected input, output and error behaviour for each operation.
Design predictable endpoints
Use consistent naming, validation and response formats. Distinguish unauthorised access, missing resources and invalid input so clients can recover appropriately.
Use the database deliberately
Choose indexes around actual query patterns and review pagination for growing datasets. Parameterised queries and clear transaction boundaries help make behaviour easier to reason about.
Keep failure visible
Record useful application errors without exposing secrets or personal data. Health checks and observability should support the way the application is operated.
Test important boundaries
Review permissions, invalid input and concurrency-sensitive changes. A successful response is only one part of the contract.
Plan deployment and change
Document environment configuration, migrations and compatibility expectations. The release process should make it clear how to verify a change and recover when needed.