VALIDATION SOURCES

Open-source notices.

ApiVect uses versioned standards and open-source components. Their authors retain their rights. The licences below apply to those components independently of our service terms.

EN16931 validation rules

Our UBL validation stage uses the European Commission's EN16931 artefacts, version 1.3.16, under the European Union Public Licence 1.2. Download the exact rule source, XSLT and licence. The complete upstream source and build instructions are freely available. We preserve the rule logic and identifiers; ApiVect supplies its own diagnostics to avoid returning invoice content.

Peppol and UBL

The additional Peppol checks use the published May 2026 rules, version 3.0.21. Read the official Peppol documentation and validation downloads. OpenPeppol owns its specification; it is not republished or relicensed here. ApiVect is an independent validation service and does not claim Peppol certification or network access-point status.

UBL 2.1 schemas come from OASIS UBL 2.1. Their original notices remain in the deployed schema files. Our synthetic downloadable example retains its EUPL licence.

XML processing

Business-rule transformations use the Saxon XSLT and XQuery Processor from Saxonica Limited, Saxon-HE 12.9. See Saxonica's licensing information, the source repository and the Mozilla Public License 2.0. XML Resolver 5.3.3 is used under Apache 2.0. The ISO Schematron compiler's source and MIT notice are available upstream.

Service infrastructure

We use unmodified Redis 8 under AGPLv3, Grafana and Tempo under AGPLv3, and Prometheus and OpenTelemetry Collector under Apache 2.0. Source code and licence notices are available from those projects. These components do not receive ownership of customer data.

For source-access questions, contact contact@apivect.com.