LanguageTool is an Open Source proofreading software for English, French, German, Polish, Russian, and more than 20 other languages. It finds many errors that a simple spell checker cannot detect.
The main reason I have moved to LanguageTool is because it can be used with LibreOffice which I do use.
Grammarly is also a good product and does seem to be the standard for corporate environments.
Please do think of the possible attack vectors of these products, an example of this is Grammarly Vulnerability that was discovered in 2018.
If you’re working on something with security concerns it might be worth disabling the add-on. This can be set up using private windows.
This tool has become fundamental for me in the work environment.
