XE Currency

Don’t bother paying up for one of the many currency conversion apps out there in the digital hinterland – this freebie is slick, easy to use, and – best of all, since it uses live currency rates – completely accurate. It’s been downloaded more than five million times to date, so don’t even think about hopping on a plane without it.
Available on iPhone (free), iPad (free), Android (free) and Windows Phone (free)