wtf is paperless-ngx-erechnung?

Paperless-ngx-erechnung is a plugin for Paperless-ngx, an open-source document management system that scans, organizes, and makes your documents searchable, that adds support for German electronic invoices (called E-Rechnungen). Starting in 2025, German businesses are required to send and receive invoices electronically in standardized XML formats. Two formats exist: XRechnung, which is a pure XML file, and ZUGFeRD (also known as Factur-X), which is a PDF that has the XML invoice data embedded inside it. Without this plugin, Paperless-ngx treats these files like any other XML or PDF and does not extract the structured invoice data, things like invoice number, date, due date, seller name, and totals. With the plugin installed, Paperless automatically detects these invoice formats when they are added to its inbox and extracts all the relevant metadata fields, making them visible in the sidebar and searchable. For XRechnung files (which are XML and have no visual format), the plugin also generates a human-readable PDF using official stylesheets from the German government's KoSIT organization and the Apache FOP layout engine. You would use this if you are a German business owner or accountant who uses Paperless-ngx to manage documents and wants incoming electronic invoices to be properly parsed and organized automatically. Installation requires adding Apache FOP and a Java runtime to the Paperless environment, which takes a few extra steps beyond a typical plugin install. The plugin is written in Python and XSLT and is licensed under GPL-3.0 to match Paperless-ngx itself.