When backwards-incompatible changes are made to the API, a new version is released. The current version is v1.
To ensure you always know about upcoming API changes, follow the Changelog.
You must specify a version in the URL with every request. By making your integration version aware, you anchor your code to a specific set of features that are guaranteed to behave in the same way for the supported timeframe.

Calling an API version

Rich Returns' API versions are explicitly declared in the URL that your integration calls:
/{ version }/{ endpoint }
For example, the following URLs call version v1: