Versioning is a product decision
Versioning is not just technical. It changes how clients experience your product. Your versioning plan should match how often clients update and how critical backward compatibility is.
If your clients update slowly, you need long support windows. If you control all clients, you can move faster.
Start with backward compatibility
The easiest version to support is the one you never create. Avoid breaking changes when possible: add optional fields, deprecate gradually, and keep defaults stable.
Backward-compatible evolution reduces support costs and keeps client integrations stable.
URL versioning
URL versioning (`/v1/users`) is visible and easy to route. It is the most common strategy for public APIs.
The trade-off is that teams can overuse it. Creating a new version is expensive; don’t make it a habit.
Header or media-type versioning
Versioning via headers or media types keeps URLs clean and emphasizes representation changes. For example: `Accept: application/vnd.example.v2+json`.
It is elegant but harder to debug, and caches don’t always play nicely without extra configuration.
Query parameter versioning
Query versioning (`?version=2`) is easy to implement but can get messy. It looks like a filter, and caching behavior can be inconsistent.
Use it as a short-term bridge rather than a long-term strategy.
Deprecation policies
Deprecation should be explicit. Provide warnings in responses or headers, publish end-of-life dates, and give clear migration instructions.
A predictable policy builds trust and reduces emergency migrations.
Testing and compatibility checks
Contract tests help ensure you don’t accidentally break clients. They catch changes in fields, data types, or behavior.
If possible, route a small amount of traffic to the new version before full launch to catch regressions.
Practical recommendation
Default to backward compatibility. Version only when breaking changes are unavoidable. Keep the number of active versions small and keep timelines clear.
Treat a new version like a product launch, not a routine refactor.