E-invoicing is now mandatory across much of the EU (Germany B2B from 2025, Austria e-Rechnung, Peppol EU-wide), and a lot of software suddenly needs to emit a valid XRechnung / Peppol invoice — not a PDF. Here's the shortest path I've found, without becoming an EN 16931 expert.
1. Start from a neutral JSON
You don't hand-write UBL. You describe the invoice in plain JSON and let the API produce the XML:
curl -X POST "https://einvoice.installateur1210.at/v1/einvoice/generate?key=demo" \
-H "Content-Type: application/json" \
