What does backward-compatible change mean in API versioning?

• A. A change that does not require clients to change their integration.
• B. A change that breaks existing endpoints.
• C. A change that requires new hardware.
• D. A change that is only documented and has no code impact.

Answer: (A)

Backward-compatible changes in API versioning are those that preserve the existing contract so current clients can keep calling the API without modifying their integration. This means you can add new capabilities or fields and adjust responses in a way that existing requests still work the same as before. For example, introducing a new optional field or a new endpoint doesn’t break callers that rely on the old endpoints and response shapes. If you altered or removed an existing endpoint or changed how a current call behaves, clients would need to change their code, which is not backward compatible. Hardware needs are unrelated to API versioning, and while documentation-only updates don’t impact code, they don’t illustrate a real, non-breaking API change.