I think Chrome uses a Google service by default. FWIW I have found Google Search's spell checker fantastic. (At least for English) It seems to have a better con

I think Chrome uses a Google service by default. FWIW I have found Google Search's spell checker fantastic. (At least for English) It seems to have a better concept of sound similarity or something that means it almost always guesses the word I mean (extra impressive because on Google Search it only shows you one suggestion). I frequently find myself in a situation where Firefox's (local) checker can't figure out what word I meant so I put it into Google Search and it nearly always knows what I meant.