Grammarly is described as 'Offers real-time grammar checks, generative AI drafting, and comprehensive feedback on clarity, tone, and style for confident and polished writing' and is a very popular Grammar Checker in the education & reference category. There are more than 100 alternatives to Grammarly for a variety of platforms, including Web-based, Windows, Mac, Google Chrome and iPhone apps. The best Grammarly alternative is LanguageTool, which is both free and Open Source. Other great apps like Grammarly are ProWritingAid, DeepL Write, Slick Write and Onit AI Copilot.
Grammark is very proficient Authors protector. It has to be used as a service and can't be downloaded into Libre Office. But it does a wonderful job in the smaller offerings that can be managed through a service.