We hope to improve it over time, the API changes won't always be backwards compatible, so we're going to version the API. This first iteration will live at https://api.payssion.com/v2/ to differentiate from the Payssion v1 version.
Please never rely on the order of the returned fields to do business processing. Only the removal of a non-optional field or alteration of an existing field will be considered incompatible changes. Clients should gracefully handle additional fields they don't expect and simply ignore them.