The ARApp displays the Stolpersteine of Cologne, in a radius of 300 meters. The App is using an OpenStreetMap. So it is possible that some of the data isn't correct or the data is not complete.
It's possible to store data of different Stolpersteine local on your device.
The App needs access to the internet, to your camera (for the AR functionality) and access to your local datastore, if you want to store the data locally.
The project was my final project during my Udacity course. The whole project is open source and can be found on Github. The link is to repro is inside the App.
And more here: http://stolpersteinear.bjoern.cologne/