Where your data lives
Split stores groups, expenses and payments on your device first. That's why you can keep working without a connection.
So that everyone in the group sees the same numbers, Split syncs the data through a server. It runs on Amazon Web Services in Frankfurt. Receipt photos are kept there in storage that is not publicly accessible.
The connection to the server is always encrypted, and data on the server is stored encrypted. A firewall protects the interface against abuse.