I don't see a point of these apps. If you can't already budget how can you remember to keep track of your spending. But maybe that's just my crap memory. 
Every now and again when I have a big enough change in my normal spending I use the spreadsheet from money saving expert to see what's my rough disposable income is and then stick to that.
http://www.moneysavingexpert.com/banking/Budget-planning

Every now and again when I have a big enough change in my normal spending I use the spreadsheet from money saving expert to see what's my rough disposable income is and then stick to that.
http://www.moneysavingexpert.com/banking/Budget-planning