Quick Validation! Rated 5 out of 5 stars

This is a great tool for web development, if you care about following W3C standards. It's also pretty useful if you want to make a point about the number of W3C errors relating to the overall stability of a website. I love that a quick glance at the bottom of my screen can tell me if any changes I made to a page are right or wrong and can easily find the offending line, all without visiting the w3c validator webpage.

This review is for a previous version of the add-on (0.8.5.8).