E-invoicing compliance, as an API — for the software you already sell
If you build ERP, DMS, accounting or invoicing software, e-invoicing compliance is not your product — it's a cost center you now have to maintain forever as EN 16931, XRechnung, ZUGFeRD, PEPPOL and a growing list of national mandates keep changing under you. INVOX is the compliance layer you integrate once, so your team keeps shipping your actual product.
Validate for free → Why not build it ourselves?
🔒 EU-hosted · zero-retention · signed, offline-verifiable proof on every result
What your engineers stop having to own
Validation. XRechnung 3.0.2 (KoSIT reference engine, 86/86 on the official test suite), ZUGFeRD 2.5.2 / Factur-X 1.09.2, EN 16931 UBL & CII, PEPPOL BIS 3.0 — plus national formats: KSeF (Poland, FA(3)), FatturaPA (Italy, 1.2.3), Facturae (Spain, 3.2.2), VeriFactu (Spain, AEAT hash chain).
Generation & conversion. Generate XRechnung/CII from your own data model, convert between UBL and CII, extract ZUGFeRD's embedded XML from a PDF/A-3 — every output is re-validated against the same reference engine before it's handed back to you.
Standard drift. When EN 16931 or a national mandate changes, that's INVOX's maintenance burden, not a sprint your team has to find room for — every format is re-verified against the official published spec whenever it changes.
Proof. Every validate/generate/convert call returns an Ed25519-signed, hash-chained attestation your customer (or their Steuerberater, or an auditor) can verify offline — without trusting your servers or ours.
Built for a vendor serving many customers, not one company
1One master account, one sub-key per customer instance. Each end customer you serve gets its own API sub-key under your account — usage, rate limits and revocation are tracked per customer. Disconnect one customer's instance without touching anyone else's.
2Sandbox first. Sandbox keys run the real validation engine — not a mock — with zero quota or billing impact, so your integration is tested against production-grade behaviour from day one.
3Webhooks, not polling. validation.completed, conversion.completed and low-credit/payment events push to your system; signed payloads, automatic retry with backoff.
4Batch. ZIP-upload many invoices in one call for bulk validation runs — built for a nightly reconciliation job, not just a single-document upload form.
Pricing that scales the way your customer base does
| Plan | Included | Price | Rate limit |
|---|
| Free | 50 validations/mo | €0 | 60 req/min |
| Starter | 2,000 credits/mo | €19/mo | 300 req/min |
| Pro | 10,000 credits/mo | €49/mo | 1,200 req/min |
| Business | 50,000 credits/mo | €149/mo | 6,000 req/min |
Overage past the included volume is transparent, graduated per credit — never a surprise invoice. Talk to us for enterprise volume, SLA or on-prem terms.
FAQ
Do we need to build our own e-invoicing rule engine?
No. INVOX is a REST API that validates, generates and converts XRechnung, ZUGFeRD/Factur-X, UBL, CII, PEPPOL BIS and several national formats — you integrate the API, you keep your own product and UI. See our build-vs-buy comparison.
Can we serve multiple end customers through one integration?
Yes. INVOX issues a sub-key per end-customer instance under one master account, so usage, limits and revocation are tracked per customer without a separate contract or integration per customer.
Is there a sandbox to build against before going live?
Yes — sandbox API keys run the real validation engine with no quota or billing impact, restricted to validate/autofix/explain, so you can build and test your integration for free.
Can we run this on-premises?
Yes — on-prem deployment is a first-class option, not an enterprise-only afterthought, for customers who legally or contractually cannot send invoice data to a third-party cloud API.
Validate for free →