XML Validator & Linter — Check XML Syntax Free Online
Validate XML syntax online. Paste your XML and get instant pass/fail with the exact error location. Uses the browser's DOMParser — runs 100% locally, no server needed.
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CommentsPaste XML to validate syntax. The browser's built-in DOMParser checks every tag, attribute, and character — returns pass/fail with the exact error location.
What is XML Validator?
XML validation checks that a document follows the well-formedness rules: matching opening and closing tags, quoted attributes, one root element, legal characters, and correctly nested elements. An invalid XML document with a missing closing tag or an unescaped & will be rejected by every XML parser. This validator uses the same DOMParser engine that browsers use for XHTML and SVG parsing — it catches every syntax error, not just obvious ones.
How to validate XML online
- 1Paste your XML into the editor.
- 2The validator parses immediately — a green banner means valid; red means invalid with the error message.
- 3Fix any errors shown and re-validate.
Frequently Asked Questions
How does XML validation work?
Our validator uses the browser's built-in DOMParser. When the parser encounters invalid XML (missing closing tag, unquoted attribute, illegal character), it reports the exact error. Valid XML returns a parse tree with no parse error.
What's the difference between well-formed and valid XML?
Well-formed means the XML follows the basic syntax rules (matching tags, quoted attributes, one root element). Valid means it also conforms to a DTD or XSD schema. This tool checks well-formedness. Schema validation requires a DTD/XSD file.
Does the tool handle large XML files?
Yes — DOMParser is fast. Files up to ~50 MB parse in under a second. The limit is browser memory, not the parser.
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