Welcome to the W3C HTML Validation Service; a free service that checks documents like HTML and XHTML for conformance to W3C Recommendations and other standards.

Validate Files

You can enter a URI in the Address field below, or choose a file to upload. There is also an Extended Interface available if you want to set any advanced options.

Recent Updates

These are the most recent major changes to this service. See "What's New" for more details.

October 06, 2001: Finished web site redesign and added Tip-of-the-Day.
September 26, 2001: Added experimental support for SVG 1.0 and spec-prod 2.0.
September 13, 2001: Added support for XHTML 1.1, XHTML Basic 1.0, and MathML 2.0.