Is there a mobile app?
No, there is not. Mining requires a lot of computational power unavailable to any of the modern smartphone or tablet yet. That is why there is no Kryptex app for Android or iOS.
Tracking your PC's activity is available directly through web-site as it is optimized for mobile platforms. There is no need in a special app to stay informed of your PC
You can use Kryptex exactly as an app by following this instruction.