The FilmHolders App allows to store the status of your large format film holders. It is a one purpose application which does not aspire to solve other problems, like registering your 35mm or 120 rolls (you find better apps for this in the store).
I have also made sure that it is easy to save and reload the data, since part of the motivation was the frustrating experience that apps come and go in the app store. So if you dont want to feel notches in the dark you might want to use this functionality;)
I appreciate everybody using it and giving feedback below. I programmed this purely for my needs and for my education but believe that I am not the only one in need of such an application.
The app is largely self-explanatory to those who have ever shot large format. It was tested extensively on my iPhone 12pro Max under iOS 15 but should work on older or newer models as well. Maybe the UI suffers a bit on smaller screens.