XML Validator
Instantly check whether XML is well-formed — shows the exact line and column of the first error.
What is an XML Validator?
An XML validator checks whether an XML document is well-formed — every opening tag has a matching closing tag, attributes are properly quoted, tags are correctly nested, there is exactly one root element, and special characters like & and < are escaped as entities.
Well-formedness is a prerequisite for any XML processing. If an XML document is not well-formed, every XML parser will reject it with an error. This validator reports the exact line and column of the first error so you can fix it quickly.
All validation runs in your browser using fast-xml-parser v5. No data is sent to any server.
Frequently Asked Questions
- What is an XML validator?
- An XML validator checks whether an XML document is well-formed — every opening tag has a matching closing tag, attributes are properly quoted, tags are correctly nested, there is exactly one root element, and special characters are escaped as entities. It reports the exact line and column of the first error.
- What is the difference between well-formed and valid XML?
- Well-formed XML follows the basic XML syntax rules checked by a parser. Valid XML additionally conforms to a schema (DTD or XSD) that defines which elements and attributes are allowed and their structure. This validator checks for well-formedness — XSD validation requires a separate tool.
- What are the most common XML errors?
- Unclosed tags, mismatched tag names, unquoted attribute values, unescaped special characters (& must be written as &, < must be written as <), and multiple root elements.
- Is my XML data sent to a server?
- No. All validation runs entirely in your browser using fast-xml-parser. Your data never leaves your machine.
- What is the difference between XML validation and JSON validation?
- XML validation checks for well-formedness (correct tag structure, attributes, nesting). JSON validation checks for correct JSON syntax (braces, quotes, commas). Both formats have strict parsers that reject any syntax error — unlike HTML parsers which are forgiving.
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