For those travelers who have accumulated some leftover foreign currencies from previous trips and are wondering what to do with it, WorldKoins is a mobile app that provides answer.
Before leaving the visited country, app users can locate a partner on the map within the app, drop-off their leftover currency and have the amount credited to their WorldKoins account. One's WorldKoins balance can be used to redeem product and online services such as iTunes cards, Google Play cards or the leftover foreign currency may be transferred to PayPal or donated for charity.
For the currencies one already has at home, it's not too late: there might be someone ready to accept it, check out the map on WorldKoins app.
Users can register as a WorldKoins partner, accept the currency of their next destination and get paid for that. To register as a partner one needs the partner app DropKoins. WorldKoins is also available in-flight on selected AirAsia flights.