W3C validators

Posted by admin at April 10, 2020

For over 15 years, the W3C has been developing and hosting free and open source tools used every day by millions of Web developers and Web designers. All the tools listed below are Web-based, and are available as downloadable sources or as free services on the W3C Developers tools site.

W3C Validator

The W3C validator checks the markup validity of various Web document formats, such as HTML.

CSS Validator

The CSS validator checks Cascading Style Sheets (CSS) and (X)HTML documents that use CSS stylesheets.

unicorn - W3C validators


Unicorn is W3C’s unified validator, which helps people improve the quality of their Web pages by performing a variety of checks. Unicorn gathers the results of the popular HTML and CSS validators, as well as other useful services, such as RSS/Atom feeds and http headers.

Link Checker

The W3C Link Checker looks for issues in links, anchors and referenced objects in a Web page, CSS style sheet, or recursively on a whole Web site. For best results, it is recommended to first ensure that the documents checked use valid (X)HTML Markup and CSS.

Internationalization Checker

The W3C Internationalization Checker provides information about various internationalization-related aspects of your page, including the HTTP headers that affect it. It will also report a number of  issues and offer advice about how to resolve them.


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