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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 , MobileOK content , or to find broken links , there are other validators and tools available.
The Markup Validator is a free service by W3C that helps check the validity of Web documents. Most Web documents are written using markup languages , such as HTML or XHTML . These languages are defined by technical specifications , which usually include a machine-readable formal grammar (and vocabulary).
CSS Validation Service. Check Cascading Style Sheets (CSS) and (X)HTML documents with style sheets
If you have no control over the page or annoying software, or your page's URL is a https one, simply append the address of the page you wanted validated (URI encoded) to the https://validator.w3.org/check?uri= address. W3C's easy-to-use markup validation service, based on SGML and XML parsers.
Sep 7, 2023 · The W3C Markup Validator is an open source software and free W3C service helping Web Document authors fix errors in the markup of their HTML, XHTML, MathML etc. resources.
Using the SOAP1.2 language over HTTP, this defines a web service with an output similar to the API for the W3C CSS validator and Feed Validator. The Full documentation for this API is available.
The Markup Validation Service is a validator by the World Wide Web Consortium (W3C) that allows Internet users to check pre-HTML5 HTML and XHTML documents for well-formed markup against a document type definition.
