#developer

A complete developer reference for Factur-X — the hybrid PDF/A-3 + CII XML format used across France, Germany, and Luxembourg. XML anatomy, profile hierarchy, EN 16931 rule mapping, validation errors, and code samples.

EN 16931 supports two XML syntaxes: UBL 2.1 and UN/CEFACT CII. Here's when to use each, how they differ technically, and why it matters for validation.

How to architect a production e-invoice validation pipeline — from single-invoice checks to batch processing with auto-remediation. Patterns, code, and deployment strategies.

Every EN 16931 validation rule categorized, explained, and cross-referenced. The definitive technical reference for e-invoice developers.

How to add a compliance layer to your ERP product: architecture, integration patterns, code examples, and the Evidence Pack workflow.

Three approaches to e-invoice validation in your pipeline: build your own, use open-source tools, or call an API. Code examples for each.