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Mustang Project VS xmlvalid

Compare Mustang Project VS xmlvalid and see what are their differences

Mustang Project

Mustangproject is a open source library and command line tool for FacturX/ZUGFeRD, a PDF-based format for electronic invoices.

Rating
0 reviews
Pricing
Open source
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Alternatives Is it good?
xmlvalid

Validate XML and e-invoices up to 1 GB in your browser: XSD, DTD, RelaxNG and official business rules

Rating
0 reviews
Pricing
Freemium $29 / Monthly (Pro)
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Alternatives Is it good?
ASocks
Clear, Fast & Unlimited. Residential & Mobile Proxies For Best Price. sponsored
Note: These products don't have any matching categories. If you think this is a mistake, please edit the details of one of the products and suggest appropriate categories.

Which is more popular?

Based on our record, Mustang Project seems to be more popular. It has been mentioned 1 time since March 2021.

social mentions
1 vs 0
Compliant E-invoicing popularity
100% vs 0%
alternatives listed
24 vs 9

Base details

Website, pricing, platforms and company facts side by side.

Mustang Project
xmlvalid
Website mustangproject.org xmlvalid.com
Pricing
Open source
Freemium $29 / Monthly (Pro) Official pricing
Platforms —
Web REST API gRPC APISOAP API
Company — Startup from Ukraine · 1 - 9 employees · 2026
Listed in
Invoicing Compliant E-invoicing PDF Tools Billing & Invoicing +1
Developer Tools APIs CI/CD XML Data Validation Finance +3

About Mustang Project and xmlvalid

In their own words, as submitted to SaaSHub.

Mustang Project
xmlvalid

No description of Mustang Project yet.

xmlvalid is an online XML validator built for production-size documents and e-invoicing. Validation XSD 1.0, DTD, RelaxNG (XML and compact syntax) 7,700+ Schematron business rules: EN 16931 (UBL and CII), Peppol BIS and PINT, XRechnung, ZUGFeRD / Factur-X, and national rules from France, Italy,...

Read more about xmlvalid

Features and specs

What each product offers, as listed by its team.

Mustang Project 0 features
xmlvalid 19 features

No features have been listed yet.

  • Schema languages
    XSD 1.0, DTD, RelaxNG (XML and compact)
  • Business rules
    7,700+ Schematron rules (EN 16931, Peppol BIS and PINT, XRechnung, Factur-X, national CIUS) plus your own .sch
  • Schema catalog
    177 official schemas with all their include files
  • Country guides
    E-invoicing in 24 countries, the profile picked from the invoice automatically
  • Max File Size
    50 MB without an account, 1 GB with a free account (5 GB tested)
  • Batch validation
    A folder or .zip of up to 1,000 documents
  • Privacy
    Validated in the browser, nothing uploaded
  • Input methods
    Upload, paste, URL, or a folder or .zip of up to 1,000 documents
  • PDF invoices
    Factur-X, ZUGFeRD and ISDOC, with PDF/A (veraPDF) and PDF text checks
  • Error details
    Line and column, explanations for libxml2, Java (Xerces) and .NET messages
  • E-invoice Detection
    Profile picked automatically from the document
  • API
    REST (OpenAPI 3.1), SOAP, MCP server, SDKs for PHP, Laravel, Symfony, Python and JavaScript
  • CLI
    CLI (npm @xmlvalid/cli), GitHub Action, GitLab CI, pre-commit
  • URL monitors
    Alerts by email or webhook when a feed starts failing
  • Reports
    PDF, HTML, JSON export, share links
  • Dark Mode
  • Integrations
    n8n, Apify, Postman
  • Monitoring
    URL monitors with email and webhook alerts
  • Free Tools
    XML formatter, XPath tester, XSLT transformer, XML diff, XML to JSON / CSV, XSD generator, XSD to XML, e-invoice viewer

Analysis

An editorial look at what each product does well and who it suits.

Mustang Project
xmlvalid

Overall verdict

  • Mustang Project (Mustangproject) is a solid, well-regarded open-source library for creating and reading electronic invoices in the ZUGFeRD and Factur-X (and XRechnung) formats, making it a reliable choice for developers needing standards-compliant e-invoicing in Java.

Why this product is good

  • It is free and open source (licensed under Apache 2.0), which lowers cost and allows customization
  • Supports major European e-invoicing standards including ZUGFeRD, Factur-X, and XRechnung, helping meet regulatory compliance
  • Provides both a Java library and a command-line tool, offering flexibility for integration and standalone use
  • Actively maintained with community support and documentation
  • Can validate, create, and extract data from hybrid PDF/A invoices with embedded XML

Recommended for

  • Java developers building e-invoicing features into their applications
  • Businesses in Germany and the EU needing ZUGFeRD, Factur-X, or XRechnung compliance
  • Companies looking for a cost-effective open-source alternative to commercial e-invoicing solutions
  • Organizations needing to validate or convert electronic invoices programmatically
  • Accounting and ERP software vendors integrating standardized invoice generation

No analysis of xmlvalid yet.

Category popularity

How often each product is chosen within a category, 0–100% relative to the other.

Score bands 0–20 21–40 41–50 51–60 61–100
Mustang Project
xmlvalid
100% 100%
Compliant E-invoicing
0% 0%
0% 0%
Data Validation
100% 100%
100% 100%
Invoicing
0% 0%
0% 0%
Finance
100% 100%

Questions & Answers

As answered by people managing Mustang Project and xmlvalid.

Which are the primary technologies used for building your product?

xmlvalid's answer:

  • 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

What makes your product unique?

xmlvalid's answer:

  • 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

Why should a person choose your product over its competitors?

xmlvalid's answer:

  • 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

How would you describe the primary audience of your product?

xmlvalid's answer:

  • 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

What's the story behind your product?

xmlvalid's answer:

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

User comments

Share your experience with using Mustang Project and xmlvalid. For example, how are they different and which one is better?

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Social recommendations and mentions

Recommendations tracked on public social media and blogs since March 2021.

Mustang Project 1 mention
xmlvalid 0 mentions
  • How to validate Peppol BIS 3 invoices in 5 lines of Python (or Node, or Go)
    If you build accounting software, an ERP, or any e-commerce flow that touches EU customers, you'll likely need to validate these invoice formats at some point. The two main open-source Schematron engines are phive (by Philip Helger of... - Source: dev.to / 6 months ago

Tracking xmlvalid since Oct 2026.

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