The You Need A Budget app for Android requires that you also use the
desktop version of YNAB. I'm including it because the Windows/Mac software will really change your finances for the better and the Android app makes it easier to stay on top of your budget and be aware of how you are spending when you're away from your computer.
Use the YNAB Android app to check budget category balances before you buy something, enter transactions and see all historical transactions in your financial accounts. The app also syncs data using DropBox or wifi so that all information is updated across all devices, whether you use the desktop or iOS app.