Rated 1 out of 5 stars

This performs the validation OUTSIDE of the browser. It sends a URL to a web site that performs the actual validation. Since the validation isn't performed inside the browser it is completely useless for validating web pages that require authentication. I am also more than a little concerned about the privacy issues surrounding this add-on. I'll be removing this add-on directly after finishing this review. I don't see how this one can be "Recommended". The only thing I recommend is to avoid it.

This review is for a previous version of the add-on (5.4.0). 

RTFM

It's a shame you didn't bother to read the description or any of the documentation, or even contacted me for help, otherwise you wouldn't have got it all so wrong.