This addon no longer works in Firefox. It worked fine for a while then just stoped, and then begged me to become a registered user. Even after registering, rebooting, delete, reboot reinstall it still didn't fix the problem. Their tech support suggested I disable my gmail signature then uninstall reboot install to fix it. Still no good.
Their Permissions are rather intrusive. Developers are in San Fancisco and the Ukraine. Having this running, assume Russia sees everything you type.
Great for basic corrections. Very, very buggy for Wordpress websites. Some corrections do not take and adds junk code to your web pages. See this site for junk code example: https://searchfacts.com/grammarly-adds-junk-code/