I love this spell and style checker! You can run it with your own local instance of of the LanguageTool back-end and enjoy a privacy-first handy little helper that rivals grammarly. Absolutely wonderful! You can integrate it into all major browsers and even Microsoft Office, although for that I think you need to turn on some undesired setting. Not sure yet.

Really lovely tool, been running it for months now with my own back-end server, definitely a "base install addon install". Also love that setup is very very easy and that it's got very good multi-language handling. No need to set your text as this or that language. Microsoft, take notes! (Especially in One Note... can't even set a language per-document... I digress :D)