Welcome to Validator S.A.C. - a stand-alone version of the W3C Markup Validator. This validator checks the markup validity of Web documents in HTML, XHTML, SMIL, MathML, etc.

Because Validator S.A.C. is a stand-alone application, it can validate local files, and pages on local servers. Validate using the stand-alone Favelet, drag and drop, or File > Open.

Validator S.A.C. can also be setup as a Web Service, allowing users to validate over the local network. See the Advanced Topics section for details.

Important This instance of the validator is either a development version used for testing purposes, or a local copy of the W3C Markup Validator software used for development and testing purposes.
The official validation service supported by the W3C is at validator.w3.org.