FinanzasOffline is an application that lets the user keep track of his financial information by registering the incomes and expences.
One of the main features is that it works fully offline, it doesn't need a backend. This means your financial information remains entirely on your device and is never transmited through the network.
There is more information in the blog post announcing the application (spanish only).
It has only been tested on an iPhone with iOS7, but should work on other platforms as well.