Threema

About

Threema is an end-to-end encrypted messenger for exchanging messages, calls, and files. The website describes three offerings: Threema Work, a business messenger with centralized management of user permissions and GDPR-compliant group chats and encrypted voice and video calls; Threema OnPrem, which lets organizations self-host the messenger on their own infrastructure; and Threema Private, which allows communication without providing a phone number or email address.

According to the website, Threema uses open-source encryption technology with Perfect Forward Secrecy and a zero-knowledge architecture, so only intended recipients can read messages. Messages are removed from servers after delivery, contact lists stay on the user's device, and reproducible builds let users verify the app's integrity. The company states it is Swiss, operates its server infrastructure in Switzerland, is GDPR-compliant, and does not sell user data or run advertising or tracking.

The website also notes that Threema Work is used by organizations such as Mercedes-Benz Group AG and the retailer EDEKA, and that a 30-day free trial with up to 30 users is available without payment details.