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HTML Validator

By Marc Gueury Free Editors' Rating

Editors' Review Staff Feb 27, 2009

This valuable freeware tool allows Web developers to check their Web pages for HTML errors. HTML Validator adds an unobtrusive icon in the right-hand corner of your Firefox window.

Hovering your mouse over the icon reveals errors and warnings for the page. Double-clicking the icon introduces a detailed window with the current Web page's lines of code, along with the errors and warnings found. The Options menu allows you to check the HTML page locally using different algorithms. A handy Help key explains what each symbol means, and novice users will appreciate the shortcut button to Htmlpedia. HTML Validator provided detailed error information for each Web page we checked. And using the Clean Up functionality, we were able to apply quick fixes to the code.

HTML Validator's straightforward design and effective presentation make it an easy tool to recommend for any Web developer, or those just interested in code.

Full Specifications

What's new in version


Release January 4, 2012
Date Added December 19, 2011

Operating Systems

Operating Systems Windows, Windows XP, Windows Vista, Windows 7
Additional Requirements Firefox 5.0 - 9.0


Total Downloads 1,347
Downloads Last Week 0
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Developer's Description

HTML Validator is a Mozilla extension that adds HTML validation inside Firefox and Mozilla. The number of errors of a HTML page is seen on the form of an icon in the status bar when browsing. The details of the errors are seen when looking the HTML source of the page. The extension is based on Tidy and OpenSP (SGML Parser).

Both algorithms were originally developed by the Web Consortium W3C. And now extended and improved by a lot of persons. Both algorithms are embedded inside Mozilla/Firefox and makes the validation locally on your machine, without sending HTML to a third party server. Each algorithm has advantages and inconvenient.