xmlvalid Reviews and Details

Questions & Answers

1. Which are the primary technologies used for building xmlvalid?

   • Rust and libxml2 (validation engine), compiled to WebAssembly
   • SaxonJS (Schematron business rules)
   • veraPDF (PDF/A checks)
   • Laravel and Livewire (PHP)
   • Tailwind CSS
   • PostgreSQL, Redis, Meilisearch
   • Cloudflare

2. What makes xmlvalid unique?

   • Schema validation and e-invoicing business rules in one place: XSD, DTD and RelaxNG, plus 7,700+ Schematron rules of EN 16931, Peppol BIS and PINT, XRechnung, Factur-X and national formats from France and Italy to Saudi Arabia, Mexico and Brazil
   • Built for large files: a streaming Rust engine (libxml2 compiled to WebAssembly) validates documents up to 1 GB in the browser with flat memory (5 GB tested)
   • 177 official schemas ready to use, and e-invoice profiles detected automatically from the document
   • E-invoice PDFs (Factur-X, ZUGFeRD, ISDOC) checked whole: the XML inside, PDF/A, and the PDF's text against the XML
   • Every error links to a page explaining why it fails and how to fix it, for libxml2, Java and .NET messages
   • The same checks in CI and integrations: REST API, SOAP, MCP server for AI agents, CLI, GitHub Action, n8n

3. Why should a person choose xmlvalid over its competitors?

   • Desktop editors (XMLSpy, Oxygen) are powerful but expensive and need installing; xmlvalid works in the browser for free
   • Simple online validators check one schema and stop at a few MB; xmlvalid streams up to 1 GB and ships schemas with all their imports
   • E-invoice validators (KoSIT, Peppol testbeds) check one format each and have no CI tooling; xmlvalid covers many formats and countries, reads PDF invoices, and has an API, CLI and GitHub Action
   • Documents are validated in the browser and not uploaded

4. How would you describe the primary audience of xmlvalid?

   • Developers and integrators building or receiving e-invoices (Peppol, XRechnung, Factur-X, FatturaPA, KSeF, ZATCA, CFDI, NF-e, UBL, CII)
   • ERP and accounting software vendors preparing for national e-invoicing mandates
   • Teams that exchange XML with partners: payments (ISO 20022), healthcare (HL7 CDA, FHIR), feeds and sitemaps
   • DevOps engineers who want XML checks in CI pipelines
   • Anyone who needs to validate a large XML file quickly without installing software

5. What's the story behind xmlvalid?

   xmlvalid is built and run by Oleksii Babintsev, a developer from Ukraine, so questions and bug reports reach the person who builds the engine. It started as a streaming validator for XML files too large for typical online tools, and grew into e-invoicing as countries made structured invoices mandatory: business rules for EN 16931, Peppol, XRechnung and national formats in 24 countries, PDF invoices, an API, CLI and GitHub Action for CI, and monitors for XML feeds. While building it, we found and fixed a slowdown in libxml2's validation of large files and contributed the fix upstream. It launched in October 2026