XE Currency The XE Currency app, which offers a conversion tool for every world currency based on live currency rates, is a must for spending abroad. The app caters to a wide range of interests, offering over 30,000 currency charts for historic rates, as well as a straightforward calculator tool for converting prices. It also stores the last updated exchange rates, so users don't have to be connected to the Internet to view conversion. Users can adjust the currency symbols included in the comparison and pin the base currency to the top of the list. To reset the list, users simply shake their mobile Apple product. This free app is compatible with iPhone, iPod touch, and iPad, but requires iOS 4.3 or later. It is optimized for iPhone 5.