Check the markup (HTML, XHTML, …) of Web documents
Validate a document online:
Upload a document for validation:
Note: file upload may not work with Internet
Explorer on some versions of Windows XP Service Pack 2, see our
on the W3C QA Website.
Enter the Markup to validate:
This validator checks the
of Web documents in HTML, XHTML, SMIL, MathML, etc.
This validator is part of Unicorn,
W3C's unified validator service. See
of checks performed by Unicorn and learn
about other tools
This service runs the W3C Markup Validator, v1.1.
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