Google Input Tools is described as 'Switch to typing in a different language with the click of the mouse, and switch back just as easily. The Google Input Tools extension provides virtual keyboards for over 90 languages, full IMEs or direct transliteration for over 30 different scripts, and handwriting input for' and is an app. There are five alternatives to Google Input Tools for a variety of platforms, including Linux, Mac, Windows, Android and Chrome OS apps. The best Google Input Tools alternative is Unistroke Keyboard, which is both free and Open Source. Other great apps like Google Input Tools are Mozc, Avro Keyboard, Translit and OpenBangla Keyboard.
It is probably the most widely used keyboard software for bengali language people on PCs.