API Design & Maintenance: Scenario-Based Questions

As APIs evolve, they must support new features without breaking existing clients. API versioning and compatibility practices help maintain trust and flexibility while evolving your platform safely.

📚 Why Version APIs?

• Prevent breaking changes from disrupting existing users.
• Allow multiple versions to coexist — stagger migration.
• Enable controlled rollout of major changes or experiments.

🔢 Common Versioning Strategies

• URI Versioning: e.g., /v1/users, /v2/orders — most common and explicit.
• Header Versioning: Use custom headers (e.g., Accept-Version).
• Query Param Versioning: e.g., ?version=2 — useful for internal/testing APIs.
• Content Negotiation: Embed version in media type (e.g., application/vnd.api+json;version=1).

⚖️ Backward Compatibility Tips

• Make fields optional when adding — never remove required ones.
• Use default values and sensible fallbacks for new parameters.
• Mark deprecated features clearly and provide alternatives.
• Support parallel versions with automated testing and contracts.

✅ Best Practices

• Document API changes with changelogs and migration guides.
• Use OpenAPI or GraphQL schema versioning tools (e.g., graphql-inspector).
• Tag metrics by API version to track usage and readiness for deprecation.
• Use API gateways to route traffic by version and apply policies.

🚫 Common Pitfalls

• Changing behavior without changing version — silent breaking.
• Leaving deprecated versions active indefinitely.
• Adding versions too frequently with minor changes — increases complexity.

📌 Final Insight

APIs are contracts. Treat them with discipline — evolution should be safe, observable, and respectful of users. Versioning isn’t just a path; it’s a promise.