QR: test TwinHelix F-Droid Repository, used for Signal-FOSS, an open-source fork of Signal Private Messenger.

Currently it serves 2 apps. To add it to your F-Droid client, scan the QR code (click it to enlarge) or use this URL:

If you would like to manually verify the fingerprint (SHA-256) of the repository signing key, here it is:
7B 03 B0 23 22 09 B2 1B 10 A3 0A 63 89 7D 3C 6B CA 4F 58 FE 29 BC 34 77 E8 E3 D8 CF 8E 30 40 28