GrammarFlip is iPad compatible. GrammarFlip was built with a responsive design which means it should work on any device (tablet, laptop, computer, smart phone, etc.). Based on the device, some resolution settings and layouts may differ and may make navigating certain pages different from others.
There is not an official GrammarFlip app right now, but a simple "add to home screen" step on your iPad will allow you to access GrammarFlip with a single click, similar to how you would access an app downloaded from the app store. Here is a simple YouTube video on how to do just that: https://youtu.be/Mvee2Ct8BTg