Postman collection

The collection has all 30 endpoints, grouped like this reference, with example request bodies.

Import and set up

In Postman choose Import and select the downloaded file.
Open the collection's Variables tab and set secretKey (and publicKey for the catalogue requests).
Run Applications → List applications, copy an ID into the appId variable, and the other application requests are ready to send. The same goes for domainId, invoiceId and the others.

Keep secret keys in Postman's Current value column. That value stays on your machine and is not synced or exported with the collection.