API Overview
Factur-X Engine is a high-performance Python middleware designed to act as a compliance gate for electronic invoicing.
- PDF/A-3 Hybrid Generation
- EN 16931 Schematron Validation
- JSON to CII XML Conversion
- Semantic Meta-data Extraction
- 100% Air-Gapped (No Telemetry)
- Sovereign Infrastructure Friendly
- Low Memory Footprint (~128MB)
- High Throughput (Native C/C++ XSLT)
- Requires Docker environment
- Input PDF must be standard PDF
- Commercial license for Full Report
System Requirements
The engine is optimized for containerized deployments. It focuses on stability and minimal resource consumption.
| Resource | Recommended | Minimum |
|---|---|---|
| CPU | 1.0 vCPU | 0.1 vCPU |
| RAM | 512 MB | 128 MB |
| Latency | < 200ms | Depends on PDF size |
Compliance & Standards
Factur-X Engine follows the semantic data model of EN 16931. It supports the following profiles:
- MINIMUM / BASIC WL Simplified tax summary
- BASIC / COMFORT Full business document
- EXTENDED Complex taxation & structures
- XRECHNUNG 3.0 Pure XML standard (Germany)
Core Workflows
The four primary e-invoicing operations: validate, generate, merge, and extract.
| Endpoint | Purpose | Input | Output |
|---|---|---|---|
| /v1/validate | Compliance gate — EN 16931 Schematron validation | PDF or XML (CII/UBL) | JSON Report |
| /v1/xml | Generate CII/UBL XML from business data | JSON metadata | XML (CII/UBL) |
| /v1/merge | Embed existing XML into PDF/A-3b container | PDF + XML | Factur-X PDF/A-3 |
| /v1/extract | Extract structured data from received invoices | Factur-X/ZUGFeRD PDF | JSON + XML |
Advanced Integration
ERP serialization and convenience shortcuts for advanced integrations.
| Endpoint | Purpose | Input | Output | Edition |
|---|---|---|---|---|
| /v1/convert | One-step: JSON + PDF → compliant Factur-X PDF | PDF + JSON | Factur-X PDF/A-3 | Community |
| /v1/serialize | ERP-ready normalized JSON from invoice | Factur-X PDF or XML | Business-Ready JSON | Pro |
Operations
Health probes, diagnostics, and observability endpoints for DevOps teams.
| Endpoint | Purpose | Edition |
|---|---|---|
| /health | Kubernetes liveness probe | All |
| /healthz | Readiness probe (JRE, VeraPDF, Saxon) | All |
| /diagnostics | Full system dump (versions, memory, config) | All |
| /metrics | Prometheus metrics scrape target | Pro |
Security Footprint
Designed for zero-trust and highly regulated environments (Banking, Government, Health).
SBOM & SLSA
Every image is shipped with a CycloneDX SBOM. We use Cosign for image signing. The software is scanned daily against CVEs.
No Remote Calls
Unlike cloud-only validators, Factur-X Engine contains all XSD and Schematron rules locally. It does not phone home to validate schemas.