Credit Karma is not a budget app, but it is an app that will help you with your budget by identifying where you are paying off debt and it can help you find ways to re-negotiate and re-finance your debt at a better rate.
This app also shows your credit score at two of the national reporters for free and will alert you if it moves too much. You can also use this app to learn how to improve your credit score. This can help you get better interest rates as you improve your credit score.
The app even searches unclaimed funds in state databases to help you track down money that you are missing from a previous job or a closed bank account and will show you how to claim that cash.
While Credit Karma isn't a budgeting app, it's one you need installed right next to whatever budget app you make your go to tool for 2018.