EN 16931 Invoice requirements — check your invoice data free

Lints invoice payloads and field mappings against EN 16931 and national CIUS rules (XRechnung, Factur-X, FatturaPA, Peppol BIS, KSeF): missing business terms, stale spec IDs, wrong mandate dates. Runs entirely in your browser — nothing is uploaded.

as of

Free here and in VS Code: Check the invoice payload or field mapping open in your editor against every rule — every rule, no key, no watermark.
The next job: Sweep every invoice mapping in the workspace and write a dated report file you keep, commit and hand to an auditor.
$29 once · one licence key per person or team seat · A German tax adviser’s time fee is fixed by StBVV 13 at EUR 30–70 per half hour.

Same engine as the VS Code extension, byte for byte.