Backend Engineering
5 API Design Mistakes That Make Applications Harder to Scale
From inconsistent responses to missing rate limits, small API decisions can create major maintenance problems.
An API is a contract between systems. Poorly designed contracts increase integration effort and make applications harder to evolve.
1. Inconsistent Response Structures
Clients should be able to predict how success and error responses are structured. Inconsistency leads to unnecessary conditional logic and fragile integrations.
2. Weak Input Validation
Validate incoming data at the application boundary. Never assume a client will send correctly formatted or trustworthy values.
3. Missing Rate Limiting
Rate limits help protect infrastructure against accidental overload and abusive traffic. They should be designed around the needs of legitimate users.
4. Inefficient Database Queries
Excessive queries, missing indexes, and unnecessary data retrieval can increase latency as traffic grows. Query performance should be measured under realistic conditions.
5. Ignoring Observability
Structured logs, metrics, and tracing make it easier to investigate failures and understand production behavior.