These requests are real. Paste a key into Authorize and every call goes to the live service. A fh_test_ key reaches the Tax Administration's test endpoint and produces a JIR with no legal effect. A fh_live_ key files a real receipt that cannot be unsent — the key prefix is the only thing that decides, and no request parameter overrides it. Use a test key here unless you mean it.

Sending to the server selected below. Each documentation site talks to the API beside it; change it in Servers if you mean to send somewhere else — but an API only accepts browser requests from the docs site it is paired with, so a mismatch fails with a CORS error rather than a response.