24pay App is the app that allows you to buy bus and tram tickets online. All you need to do is to download the App, complete with your data and then scan the Qr code that you'll find in every bus and tram. Some of the cities from Romania use exclusively the App in order to buy tram and bus tickets. The ticket is available 2 hours from the moment you bought it, indifferent of the bus or tram you are in.