LanguageTool works well for me - it is less obtrusive than tools I've used in the past yet enables me to ensure my posts are better than they would be otherwise. Features such as the ability to add unusual words, acronyms, or names to my local dictionary or ignore them, and the ability to navigate to the context of a typo, and also, to ignore suggestions easily if I want to. I have not yet tried a language other than English. I have been especially grateful for LT when I have been unaware a key or two on my keyboard has stopped working. How terrific to see the LT prompt when about to post a quick note in which all letter 'u's would have been omitted. Many thanks to LTers for providing stronger support for privacy and developing a convenient and effective tool!