You can use the extension even without registration and sharing your email, the only grammar checker I know with such a function.

Very helpful, would be better if worked everywhere, but almost all my favorite sites are covered (email, blogging and social networking sites).

I've started using this in December 2018, was one of the first users, and I see big progress since then. First of all, they now have browser extensions which is super handy. I use the web app as well, and its statistical module gives good feedback on readability.

It works much better than usual built-in browser writing enhancement tool.!