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XML Validator
Check whether an XML document is well-formed
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About this tool
Check whether an XML string is well-formed — catches mismatched tags, missing closing elements, and structural errors.
Frequently asked questions
What does "well-formed" mean for XML?
It means the basic syntax rules are followed — every tag is properly closed and nested, attributes are quoted, and there's exactly one root element. It's different from "valid against a schema" (like a DTD or XSD), which this tool doesn't check.
What kind of errors does this catch?
Unclosed tags, mismatched opening/closing tags, invalid characters, and multiple root elements are the most common issues it will catch.