- Proprietary Google libraries
This uses proprietary Google libraries for clients
Relying on Google Play
It seems that users have to install the Google Play app on a smartphone to verify their accounts (tied to a phone number). I don't see the app in the F-Droid repository, so it seems that even if Signal is free software itself, users are forced to use proprietary software. I think this app should be removed from the directory.
Proprietary dependency on Google libraries
"Signal, a messaging app for mobile phones, has earned widespread deserved praise as a free software encrypted voice and text communication client, but currently has a proprietary dependency on Google libraries. Helping the project remove this dependency and operate the necessary infrastructure is a high priority." - https://www.fsf.org/campaigns/priority-projects/voicevideochat
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