Why normbill
Two honest comparisons.
Against the free open-source libraries, and against the legacy e‑invoicing providers — including when not to pick us.
Why pay for this?
The free library generates the XML too. Here's the part it leaves on your desk.
horstoeko/zugferd and Mustangproject are solid, genuinely free libraries. If all you need is to emit the XML, use them. What they hand back to you is everything after that.
The free library
Generate the XML
Yes — one POST
Yes — solid libraries, genuinely free
KoSIT validation
Managed — every response is validated before you see it
You run the official validator yourself: Java sidecar, config, updates
Error messages
The exact field in your JSON + a plain-language fix
Raw Schematron codes (BR-DE-15, line 47)
Version upkeep
We ship updates; your integration doesn't change
You track every XRechnung / KoSIT release (2× a year)
Formats
XRechnung UBL/CII, ZUGFeRD / Factur-X PDF, Peppol BIS, parse — one JSON model
Broad — Mustangproject alone spans ZUGFeRD, Factur-X, XRechnung and Order-X
What you operate
Nothing — one HTTPS call
A JVM or PHP runtime, the KoSIT validator, its config, and every release bump
WHEN THE LIBRARY WINS
If you want zero external dependencies and have a team ready to own compliance updates, the open-source libraries are the right call — use them. normbill is for teams who'd rather ship and never think about a Schematron release again.
The alternative
E‑invoicing APIs were built for procurement departments. This one is built for you.
Legacy providers
First API call
Under 5 minutes
Days — after the demo call
Entry price
€0, no contract
Quoted on request, annual contract
Getting an API key
Instant, self-serve
After a sales call
Contract
Monthly, cancel anytime
Annual, with minimums
Sandbox
Free test mode, 1,000 calls/mo
“Contact us”
Documentation
Public, with runnable examples
PDF, on request
Validation errors
Plain-language fixes
Schematron rule codes
Be mandate‑ready this afternoon.
Free key, 50 invoices a month, full validation. Upgrade only when you're shipping real volume — no sales call, no contract, no credit card.
✓EU-hosted✓No invoice data stored✓GDPR-first✓30-day validation guarantee