Which personal information is saved?

In theory none, in practice some.

In general the app does not save any personal data and it is also not my goal to collect any userdata. But it has to be said that some features need sensible data and you should be aware that these data have to be stored as well.
These data include:

INSTALLATION-ID:

Upon installation the app generates a random installation-id, which will be saved to each of your receipts. The app uses this number to determine which user of a database belongs to a receipt.
Be arawe, that this number is completely random an can not used or viewed by other apps. This means that the installation-id can not be used to detail any personal information. So, even though I think that this number should not lead to security concerns, I still think it is important for you to know that receipts are not stored independently from each other on the server.


GPS-LOCATION:

If activated, the app can use your current gps-location to make it easier to recognize the location of a receipt. This data is also used to generate a map of all purchase-locations. The GPS-location is completely voluntary and is not needed for the app to work properly (it is just a feature and an aid).
Should you decide to use the GPS-feature, please be aware, that these data will be stored in this app and will also be uploaded to the server if synchronisation is enabled.


FINANCIAL DATA:

Hopefully that should be obvious: The data that is saved by this app can be used to infer the financial situation of a useraccount (and depended on the products and location of the receipts possibly also the user identity?)

How secure is the data?

All data is transferred over a secure connection to the server. And aside from myself, no one else has access to the data.

Will data ever shared to anyone else?

NO
All data will NEVER be shared for processing, for advertising purposes or for any other reasons. I personally have no interest in sharing the data to anyone ever.

What happens with the data?

At the moment data is only used for synchronisation.
I am thinking about maybe calculating some global statistics out of the data (for example comparisons about the income and expenses between different countries) and maybe publish these results somehow. But at max, data will ONLY be used for statistical purposes (and only by mself). I will never ever process data that can be used, in any form, to infer information about Individuals.