This is the best web highligher addon on Firefox browser at the moment. A similar one that works on Chrome is web highlights, but the developer doesn't seem to have any plans to extend it to firefox, which means that this addon has no competition on firefox. Hopefully the author will do the English language work so that more international users can use this addon. Maybe you can give this addon an English name and make a introduction video on Youtube. I am sure with the current pricing it can attract a lot of international users to pay for the subscription.