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