Youth Card App lets you browse activities available for youth in your region, register to them and log visits. It displays your personal QR code and includes a QR scanner for scanning visits yourself.
The activities and events are managed on regional Youth Card websites:
Finland - https://nuortenjoensuu.fi
Germany - https://dresden-youthcard.eu
Czech Republic - https://youthcard.cz
Croatia - https://medimurje.youthcard.eu/
Portugal - https://lousada.youthcard.pt