Type2phone - Type2Phone: Use your Mac as keyboard for iOS devices
Gboard - Google-powered keyboard with search, GIFs, emojis and more!
1keyboard - Type on your iPhone, iPad or AppleTV using your Mac keyboard
AnySoftKeyboard - Android (f/w 1.5+) on-screen keyboard for multiple languages.
Mocha Keyboard - Mocha Keyboard is a leading Bluetooth keyboard application for iPad, iPhone, and iPod touch.
Fleksy - Fleksy is the #1 private, white-label virtual keyboard SDK, enabling companies to create unimaginable products.