Grammarly sends up to 10k DNS requests to it's servers every day. That's 380 requests per hour! or 6.3 requests per minute! Queries servers are grammarly.io, grammarly.com, grammarlyaws.com.
Why would they do that?? Why would grammarly addon ask for IP of mothership server so often? Uninstalling this.

UNABLE TO GET GRAMMARLY ON FACEBOOK.

It is wrong more often than correct. It works halfway decent on spelling, but grammar is wrong most of the time.