While Kaleidoscope is Mac only, Diffchecker is cross-platform and still under active development. We just released Dark Mode and Spreadsheet diff is on the way

While Kaleidoscope is Mac only, Diffchecker is cross-platform and still under active development. We just released Dark Mode and Spreadsheet diff is on the way (while Kaleidoscope has seemingly stopped development in late 2017). It's still a great tool though that works for a lot of people.