Hence, the service can be used anonymously. Linking a phone number or email address to a Threema ID is optional. It is possible to find other users by phone number or email address if the user allows the app to synchronize their address book. Threema uses a user ID, created after the initial app launch by a random generator, instead of requiring a linked email address or phone number to send messages. This helps anonymize the users to a degree. The service claims to be based on the privacy by design principles by not requiring a phone number or other personally identifiable information. Threema is available on iOS and Android and has clients for Windows, macOS, Linux, and can be accessed via web browser but requires a mobile app to function. Unlike many other popular secure messaging apps, Threema does not require phone numbers or email address for registration, only a one-time purchase. Users can make voice and video calls, send photos, files, and voice notes, share locations, and make groups.

The service operates on a decentralized architecture and offers end-to-end encryption. Threema is a paid cross-platform encrypted instant messaging app developed by Threema GmbH in Switzerland and launched in 2012. ( November 2015) ( Learn how and when to remove this template message) The references used may be made clearer with a different or consistent style of citation and footnoting. This article has an unclear citation style.

Threema vs signal