All responses from the Billwerk+Optimize API will be in JSON. All responses will contain a unique request identifier in the HTTP headers with name Request-Id. The request-id allows Billwerk+Optimize to find requests in cases where troubleshooting is necessary.
Billwerk+Optimize follows an open for extension, but closed for modification API strategy, meaning that new attributes can be added, but no required attributes are removed. It is important that integrations are implemented to ignore unknown attributes.