The IRMA app manages your personal IRMA attributes: you can receive new attributes, selectively disclose them to others, and attach them to signed statements. These attributes can be relevant properties, such as: "I am over 18", "my name is ..." and "I am entitled to access ....". They are only stored on your device and nowhere else.
IRMA is made and maintained by the Privacy by Design Foundation, and freely available and open source. Find out more at: https://privacybydesign.foundation/irma-en/
The source code of this app is available as open source on: https://github.com/credentials