The Lucia app is capable of generating QR codes that users can use to check in at locations while not providing any personal data whatsoever. This is intended to safe-guard your privacy against a security hole in a certain system that might be forced upon you by some institutions.

QR Codes generated by Lucia can be presented to a staff member at the location to scan it from your smartphone. It will be considered valid by the check-in system. It does not, however, contain any personal data about you.