On Android, the Wallaby app (which you can load which cards you have and it will often tell you which card is best to use for maximizing rewards) used to be great for me. Lately though, it's a buggy mess that requires me to log in every time I use it. This seems to be a pretty common problem from looking at some of the app reviews lately.

I was wondering if anyone had used anything similar on their mobile phones for this? Some kind of Wallaby alternative?