1. Generate ZUGFeRD from existing invoice data
Use the data already present in billing, ERP, shop or marketplace systems.
ZUGFeRD API
ZUGFeRD API for existing systems
ZUGFeRD is most useful when it comes directly from the system that already creates invoice data. Fakturai is built for that boundary: existing data in, technically checked ZUGFeRD / Factur-X output out.
The proof is public. You can inspect the sample payload and passed technical validation report before discussing an integration.
ZUGFeRD proof
The sample JSON shows a concrete test invoice with seller, buyer, line item, 19 percent VAT, due date and delivery date.
The validation report lists the format as ZUGFeRD / Factur-X EN 16931, the KoSIT validator with profile EN16931-CII and no hard technical failures: hard_failures: [].
Note: Fakturai checks the technical format. The invoice issuer remains responsible for invoice content, tax treatment and archival.
public ZUGFeRD proof · Technically validate an existing invoice
2. API boundary instead of manual export
The integration should be repeatable: send request, receive technical output, inspect validation report.
3. Validation report as a developer signal
hard_failures: [] is a technical signal for this sample flow. It is not a replacement for invoice content approval.
4. Good fit criteria
Existing invoice data source, developer access and a need for API-first ZUGFeRD output.
5. Boundaries
Do not claim third-party endorsement. Do not promise legal or tax validity.