XML Validator
Validate XML syntax
Frequently Asked Questions
What does the XML Validator check?
The validator checks well-formedness: proper tag nesting, matching open/close tags, valid character encoding, correct entity references, proper attribute quoting, and XML declaration syntax. It reports all errors with line numbers.
What is the difference between well-formed and valid XML?
Well-formed XML follows basic syntax rules (proper nesting, matching tags). Valid XML is well-formed AND conforms to a schema (DTD, XSD, or RelaxNG) that defines allowed elements, attributes, and structure. The validator checks both.
Can I validate XML against an XSD schema?
Yes. Paste your XML and XSD schema. The validator checks that the XML conforms to the schema: correct element names, required attributes, data types, cardinality constraints, and enumeration values. All violations are reported.
What are common XML errors?
Mismatched tags (<div>...</span>), unescaped special characters (& instead of &), missing closing tags, attributes without quotes, invalid characters in element names, and duplicate attributes on the same element.
Does the validator handle large XML files?
The validator processes files up to 5MB in the browser using streaming parsing. For larger files, it validates in chunks to avoid memory issues. Error reporting includes line and column numbers for quick navigation.