W3C Markup Validation Service

Check the markup validity of web documents with W3C Validator

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Provided by W3C Nu Html Checker
W3C

About W3C validator

The W3C Validation Service is a free software created by the W3C to help Web designers and Web developers check document (HTML, XHTML, SMIL etc).

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Documentation

Learn more about the documentation index and developer resources for W3C Markup Validator.

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