How would you version APIs for address management without breaking clients?

• A. Apply semantic versioning, maintain backward compatibility, deprecation timelines, and provide migration guides.
• B. Change the base URL for every new version without notices.
• C. Versioning is unnecessary if you have good tests.
• D. Always update the API in the client, not the server.

Answer: (A)

Versioning APIs without breaking clients relies on treating the API as a stable contract and signaling changes clearly. Semantic versioning gives a precise way to communicate how changes affect compatibility: a major version indicates possible breaking changes, while minor releases add features in a backwards-compatible way and patches fix issues without altering behavior. By aiming to preserve backward compatibility whenever possible, existing integrations keep working without immediate updates. When a change would break existing clients, you introduce a new major version and publish a clear deprecation timeline, so developers know when to migrate. Providing migration guides, documentation, and sample code helps teams update their integrations smoothly. Hosting multiple versions in parallel (for example, versioned endpoints or media types) lets clients move at their own pace rather than being forced to change immediately. The other approaches undermine stability: changing the base URL for every new version with no notices disrupts existing clients; relying solely on tests doesn’t guarantee that external integrations won’t be affected by API contract changes; updating the client without server-side versioning fragments maintenance and creates inconsistency.