There is a tried and true method for keeping within a budget. Take your monthly salary and split your spending budget into four envelopes. Each week you open an envelope to add to your allowance. This allowance is used on consumables, not your monthly bills. This will help you stay within your budget.
This app is like those four envelopes. You routinely add to your allowance and manage your spending in accordance with that allowance. Personally I add to my allowance on Mondays so I won't blow it all over the weekend.
I purposely made the app extremely barebones and simple, you only have one budget to track. This keeps things focused on your daily spending leaving bills and other unavoidable expenditure out of sight.
This approach is what has helped me keep to a budget and I hope it will help you too.
The app has an extra feature I want to explain. The shopping cart is a feature where you can keep track of how much you have in your cart while in the store shopping for groceries. This way you can easily make sure your shopping cart won't exceed your allowance and maybe you'll make smarter choices.