Most API failures don’t come from “complex” problems.

Instead, from basic design mistakes…

Here are the biggest API design mistakes I see 99% of YOU making:

1. Using verbs instead of clear resource names.

   • Your API endpoints should represent ‘things’, not actions.

   • Keep your URLs simple… and predictable.

2. Ignoring “standard” HTTP methods.

   • If everything is POST,,, nothing makes sense.

   • GET, POST, PUT, PATCH, DELETE exist for a reason… follow semantics to make APIs intuitive.

3. Forgetting idempotency in critical operations, such as payments or orders.

   • A duplicate request should NOT charge a user twice.

   • Use idempotency keys or database constraints.

4. Deploying APIs without versioning.

   • Don’t break clients with changes… instead, maintain “backward compatibility”.

   • Version APIs using URL or Accept headers.

5. Returning vague/unsafe status codes.

   • Errors should be actionable, consistent & safe to expose.

   • Remember, status codes are part of your API contract.

6. Not using PAGINATION at scale.

   • Use ‘offset pagination’ for simple use cases.

   • Use ‘cursor-based pagination’ for real-time & big datasets.

7. Not filtering or sorting at scale.

   • Use query parameters & proper database indexing for fast queries.

8. Treating security as an afterthought.

   • Use OAuth, JWT, or API keys.

   • Also, always validate tokens.

9. Skipping rate limiting.

   • If you don’t protect your API,,, someone will abuse it.

   • Plus, don’t forget to return relevant headers & status code when the threshold exceeds.

10. Not caching correctly.

    • Apply HTTP caching headers.

    • Cache frequent responses to reduce latency & costs.

11. Shipping undocumented APIs.

    • Use Swagger/OpenAPI.

    • Document endpoints & examples.

12. Treating REST like a ‘religion’.

    • Remember, REST is a guideline… NOT a rule.

    • Consistency & clarity matter more than purity.