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 request, generated PDF and passed technical validation report from a production run before you integrate.
ZUGFeRD proof
The request JSON shows a synthetic test invoice with buyer, line item, 19 percent VAT, due date and service period. Seller details come from the account profile.
The validation report for the generated ZUGFeRD / Factur-X EN 16931 invoice shows KoSIT accept, PDF/A compliant and no hard technical failures: hard_failure_count: 0, plus six XRechnung/Peppol advisories.
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_failure_count: 0 is a technical signal for this invoice. 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.