About XML Validator

Validate XML syntax and well-formedness. Part of the DevTools Surf developer suite. Browse more tools in the XML collection.

Use Cases

• Integration engineers validating SOAP messages against WSDL schemas
• Java developers checking Maven POM files for syntax errors
• Data engineers ensuring XML feeds conform to agreed-upon schemas
• DevOps engineers validating XML deployment descriptors before releases

Tips

• Check well-formedness first before validating against a schema
• Read error line numbers to pinpoint exact validation failures
• Validate frequently during editing to catch issues early

Fun Facts

• XML Schema Definition (XSD) became a W3C Recommendation in May 2001 and remains the most widely used XML validation language.
• A well-formed XML document must have exactly one root element, a rule that trips up many beginners.
• RELAX NG, an alternative to XSD, was designed by James Clark and Murata Makoto and became an ISO standard in 2003.

FAQ

What does the XML Validator check?

Well-formedness (balanced tags, proper nesting, valid entity references) plus XSD structural validation when a schema is provided. For DTD validation use a dedicated tool.

Can I validate against an inline DTD?

Internal DTDs are parsed but structural checking is limited. For full DTD enforcement, upload an external DTD or use xmllint locally.

Does it check character encoding?

Yes — BOM detection, XML declaration encoding verification, and invalid character sequences are all reported.

Will it report every error or stop at the first?

Every error with line/column. This is slower than stop-on-first but far more useful when you're triaging a large broken document.