A free program for Android, by Theme Design Apps for Android.

Pink RGB Heart Keyboard Theme is a wonderful application that will make your phone look so amazing. If you are tired of the plain and boring keyboard on your phone, you should definitely try this one. It will definitely make your phone look very beautiful. This application is very easy to use, and you will not need to do anything special to use it

This platform also features over 3000 colorful themes, including DIY support, customizable keyboard colors, a bunch of wallpapers,  an assortment of layouts, over thousands of emojis, dictionaries, GIFs, emoticons, and stickers. This app is constantly updated.