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They are useful, Grammarly at least. I haven't used Hemingway because when I tested it, there were a lot of things it missed. But Grammarly is great :) Thanks

Hemingway isn't a spell check in the same way Grammarly is. the point of Hemmingway is to highlight the parts of your writing that need a little bit of clarification. so they do different things, though there is some overlap (like passive voice).

I use both on everything, most everything anyway, that I write.