We do not recommend external apps such as Stocard, Fidme, MyShopi, etc. to monitor you Joyn account. You run the risk that your QR code will not be read correctly or that your points balance will be displayed incorrectly.
With the Joyn app you can simply manage your account, keep track of your points balance and rewards, and see the various Joyn merchants near you at a glance.
The Joyn app works with both iPhone and Android and is very easy to install. Read here about how to install the app on your smartphone for iPhone and for Android.