Rated 5 out of 5 stars

Poor HTMLValidator, poor Marc.

Firefox has problems but all we notice is that an extension is not prepared to cope with the bad attitude of the Firefox-developers.

I love this extension and will rather stop using Firefox than do without HTMLValidator!

Having overcome the worst trouble with the 10.x releases of the browser, I am glad to say, that the extension works fine under Linux 64Bits.

This review is for a previous version of the add-on (0.9.5.1.1-signed). 

Enjoy is the word. Rated 5 out of 5 stars

What do you want to compare this extension to? Never before had it been so much fun, to bat ones fingers with a heavy tool.
Addition 2007-04-23: No speed problems here.

This review is for a previous version of the add-on (0.8.4.0).