The Austrian Red Cross developed the "Stopp Corona" application

The intent of the Stopp Corona-App is to help interrupt the chain of infection of the Corona virus as fast as possible. It uses an anonymous contact diary which logs personal encounters using a "digital handshake". If one person shows symptoms of the corona infection, all those who "digitaly shook hands" with that person will be automatically informed, that one of their anonymous contacts shows signs of an infection. They are then asked to isolate themselves aswell to reduce the risk of infection others and break the chain of infection. This way fewer people will be exposed to a potential infection. Additionally, this system supports and relieves doctors, who would otherwise have to go through this process manually. 

More infomation about the application is available on the website of the Austrian Red Cross.