No, Grammarly is not malware.
Malware is a type of illegal software that is created to harm your device. It is also known as "malicious software."
Grammarly’s products check your writing and provide text corrections. They do not damage your device or the information stored on your device. Unlike most malware, Grammarly cannot run on your device unless you choose to install it. You may uninstall Grammarly at any time and remove it from your device.