Recommend a Firefox plug-in--html VALIDATOR (based on Tidy), now is version 0.79, installed on the plugin, in Firefox is very easy to test your HTML code, download here: http:// Users.skynet.be/mgueury/mozilla/download.html, FF will be installed online, restart ff, ie download files after copying to the Firefox installation directory under the Extensions folder, The next time Firefox start will automatically install, I tried, in the 1.07 version can not be successfully installed, FF1.5 can be.
If you have questions to see: http://users.skynet.be/mgueury/mozilla/faq.html .
When used, start FF to open a Web page, and the results of the test will appear in the lower right corner of the screen. To see the detailed results, you can choose to view the source file, in the Open window, the toolbar will be added a tool button, view the source file at the same time to start testing the Web page code, such as the modified, optional reload, the following figure, Try, and the results of the global consortium is somewhat different, it is divided into fault and warning, generally speaking, or more convenient to use.