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 (Full Document) to validate:
This validator checks the markup validity of Web documents in HTML, XHTML, SMIL, MathML, etc. If you wish to validate specific content such as RSS/Atom feeds or CSS stylesheets or to find broken links, there are other validators and tools available.