Versioning

The Partner API is versioned in the URL path, per resource:

https://api.unitedpetclub.com/api/{resource}/v1/…

There is no version header and no Accept-based negotiation — the path is the whole contract, which keeps requests copy-pasteable and easy to route. The current version of every resource is v1.

What changes without a new version

Within a version, changes are additive only. Expect, and code defensively for:

new optional query parameters and new optional request fields;
new fields on response objects;
new operations and new resource families;
new values in enumerated string fields.

Build your client to ignore fields it does not know and to treat unknown enum values as “other”, and additive changes will never break it.

What requires a new version

Anything that could break a correctly written client ships under a new path segment (/v2/) for that resource, with the previous version kept alive in parallel:

removing or renaming a field, parameter or operation;
changing a field’s type or meaning;
tightening validation so previously valid requests fail;
changing authorization requirements for an existing operation.

How changes are announced

Every change — additive or breaking — is recorded in the Changelog, and breaking changes are announced there before the old version is retired. Pin your integration to the version you tested against and read the changelog before upgrading.