About the W3C Log Validator

The Log Validator combines a Server Log analysis engine with batch validation, link checking and other quality-oriented processing, for step-by-step improvement and maintenance of Web Site Quality.

More W3C Software

W3C develops many more software tools. See the other Quality Tools (validators, etc), or the list of all W3C Open Source Software.


Validator(s) mailing-list at W3C.

Log Validator mini-FAQ

What is this?

A free, simple and step-by-step tool to improve dramatically the quality of your website. Find the most popular invalid documents, broken links, etc., and prioritize the work to get them fixed.

Who should use this?

Anyone writing or maintaining websites, especially large ones.

Where is the documentation?

All the information on how to use this tool is in the Manual.

Where do I get it?

See the download instructions.

I'm a developer, can I help? ・ Where can I report bugs?

The tool is open source, developers are welcome to help, and bug reports are welcome, too. See below for details on participation and feedback.

Still unclear what exactly the tool does?

The "Philosophy" of the LogValidator

Step-by-step quality

Log Validator is a web server log analysis tool with focus on the quality of Web documents. Thanks to a modular, extensible design, the Log Validator can help Web authors find the most popular content on their web site that matches particular criteria.

The Log Validator was first written with Validation (HTML, etc.) in mind : it can thus help web content managers find and fix the most frequently accessed invalid documents on their Web site, acting as a comprehensive, step-by-step validation tool.

What this tool does (and does not)

This tool takes a web server's last logs and processes it through validation modules. Those validation modules check the most popular documents' validity for a certain technology . The default module is HTML validation, but there are others available (see the list of modules for supported technologies).

The (X)HTML validation module, for example, helps you find, among the most popular pages on your site, which are invalid, and thus tell you which (invalid) pages you should fix first. This is a step-by-step process, you can set up this tool to run every week, and painlessly fix only a few documents at the time. Eventually, you will have fixed your whole site, or at least the most important parts of it. (see also tips for the HTML module)

A bit of History

Since 1994 and the first HTML validator service, there has been a way to check the validity of one's webpage with regards to web standards (HTML, CSS, ...). Other services, like HTML Tidy allow you to (semi-)automatically fix invalid documents...

This tool is here to make your life as a webmaster, web designer, web developer even easier, by telling you which documents you should fix in priority.

It has first been developed by Gerald Oskoboiny as an internal W3C tool (yes, even at W3C we create invalid HTML sometimes) to check the HTML validity of the webpages on the W3C website, then released its code in september 2001.

In 2002, the Quality Assurance team at W3C decided to re-write it as a modular, portable, and easy-to-use tool for webmasters. Its development continues, mostly with the addition of new processing modules making the Log Validator a very useful and versatile Web Quality analysis tool.

How to Participate

bug reports

Anyone is welcome to provide bug reports, bug fixes, improvement and patches, ideas, etc. Submissions should be sent to the www-validator mailing list (send mail). Please note that any mail sent to this list will be publicly archived and available, do not send information you wouldn't want to see distributed, such as private data.

Source code for this tool is available under the W3C Software Licence.

Additional modules

You are welcome to develop and submit additional modules (learn more about the Modules creation documentation and API for the modules).


Translation of the documentation is welcome. If you translate these documents, please contact us so that we can include your translation to the alternate versions of this manual. (See more about translations of W3C documents).


Many thanks to...

Valid XHTML 1.0! Created Date: 2002-07-24 by Olivier Thereaux
Last modified $Date: 2007/08/31 00:08:12 $ by $Author: ot $