Is my shop’s data kept separate from other shops?
Yes. Every business’s data is isolated at the database level rather than by application code alone, so one shop cannot read another’s records even in the event of a bug in the app. Access within your own shop is controlled by the role permissions you set.
Your data is stored in the European Union, and access is over HTTPS throughout.
For the records that matter most — the money ledger, completed sales, the audit log — entries are append-only. A correction is recorded as a further entry rather than by editing history, so the trail cannot be quietly rewritten.