We version our public API to support backwards-incompatible changes. As
our product grows and changes our semantics do as well, and we want our public
protocols to reflect that. This helps us enforce the sort of guarantees we want
to offer to both our Publisher and Brand partners.

The first time your Organization makes a request to Button's public API, your
version is pinned to the latest published version. Your version is guaranteed
to never change, and you should never experience backwards-incompatible
responses, errors, or side-effects of any API calls (sometimes we might introduce
backwards-compatible changes like accepting an additional parameter).

API Versions are labeled by the date they were introduced in YYYY-MM-DD
format. Importantly, API Versions are cumulative: all protocol changes
introduced at or before your current API version will be in effect for all of
your requests.

Published API Versions

2018-02-13
- Require purchase_date on POST /v1/order