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In light of recent events: Threema and the address book

The question whether Threema can be used without access to the address book has been coming up a lot lately. The answer is “Yes”, of course.


According to Germany’s Right to Informational Self-Determination (“Recht auf informationelle Selbstbestimmung”), it is up to each individual to decide about the use and the disclosure of their personal data. Thus, if a messenger requires access to the address book, a potential user is confronted with two choices:

  • to ask all address-book contacts for permission to share their contact details with the messenger operator
  • to not use the messenger

Threema: No access to contact details required

Unlike ordinary messengers, Threema doesn’t use the phone number to uniquely identify users. Instead, the Threema ID serves this purpose. The Threema ID is a randomly generated string; no conclusions about the user’s identity can be drawn from it. And since linking a phone number or email address to a Threema ID is optional, Threema can be used completely anonymously.

In Threema, users enable or disable contact synchronization at their own discretion. (Detailed information about contact synchronization can be found here.) It’s not necessary to grant Threema access to the address book. If no access is granted, contacts can be added manually by entering their Threema IDs or by scanning the respective QR codes.

As far as chat apps are concerned, there is a lot more to privacy protection than mere message encryption. Find out how common messengers hold up against Threema’s strict privacy standards in this comparison.