AnySoftKeyboard - Android (f/w 1.5+) on-screen keyboard for multiple languages.
FlorisBoard - An open-source keyboard for Android.
Gboard - Google-powered keyboard with search, GIFs, emojis and more!
Hacker's Keyboard - Are you missing the key layout you're used to from your computer when using an Android device?
Multiling O Keyboard - Super lightweight (~ 1/3 MB) yet flexible and powerful soft keyboard.
Grammarly Keyboard - If you want your mobile writing to truly shine with its polish, you need the Grammarly Keyboard