CarPal is the first mobile application of ridesharing mixing navigation and integrated billing system. Besides, this application allows, for the first time, instant ridesharing (automatic updating of ridesharing offers all along drivers routes) as well as classic ridesharing (or planned in advance). It brings flexibility and real safety to the practice : share your ride in quite freedom, whenever you want, without planning and without change, only with your smartphone and your PayPal password.This application is a real tool of sustainable development.