Hi folks 👋, Michael here, maker of normbill.com ! Quick context for everyone outside Germany: from January 2027, German companies with >€800k revenue must issue structured e-invoices (XRechnung) for domestic B2B . Everyone else follows in 2028. That means every software product where users create invoices needs to ship this feature in the next few months. You send invoice JSON, you get back compliant XRechnung (UBL or CII), validated against the official KoSIT validator. Germany's legal reference implementation. And when validation fails, every finding is mapped back to the exact field in your request, with a plain-language explanation and a concrete fix. The 422 response is honestly the thing I'm most proud of. A few things that matter for this space: invoice content is never stored (processing is request-scoped, EU-based), there's a free validator you can use without an account, inbound invoices (UBL/CII) parse back into JSON, and ZUGFeRD/Factur-X hybrid PDFs are supported. SDKs for TypeScript and PHP. Honest note: if you have a Java team and want to own e-invoicing entirely yourself, Mustangproject is solid open source.I compare the trade-offs openly in the docs. normbill is for teams who don't want to own KoSIT updates, decimal rounding math, and Schematron decoding forever. You can try it without signing up.The playground runs the validation engine right in your browser. Hope you like it! Cheers!

normbill

valid XRechnung — or the exact reason why not

valid XRechnung — or the exact reason why not