No, Grammarly is not a keylogger.
A keylogger is a program that records every keystroke you make, in any program, on a particular device. Cyberthieves sometimes use keyloggers to steal personal information, such as passwords.
Grammarly does not record every keystroke you make on your device. Grammarly accesses only the text you write using a Grammarly product, and only for the purposes of checking your text and providing corrections. Additionally, Grammarly does not process anything you type in text fields marked "sensitive," such as credit card forms or password fields.
You can find instructions for deactivating any Grammarly product in the Tips & Tutorials section of our Support portal.