Threema

Threema is a privacy-focused instant messaging application developed by Threema GmbH, headquartered in Pfaffikon, Switzerland. Founded in 2012 by Manuel Kasper, Threema distinguishes itself from other messaging apps by not requiring a phone number or email address to register. Instead, users receive a randomly generated Threema ID, enabling truly anonymous communication. All messages, calls, and shared media are end-to-end encrypted using the NaCl cryptography library.

The platform supports text messaging, voice and video calls, group chats, polls, file sharing (up to 100 MB), and a built-in QR code contact verification system that lets users confirm the identity of their contacts in person. Threema also offers Threema Work for enterprise use, which includes device management, app configuration, and a management cockpit. Threema Broadcast enables organizations to send one-way communication to large groups, useful for internal communications and announcements.

As a Swiss company, Threema benefits from Switzerland's strong privacy legislation and operates entirely outside of EU and US jurisdiction. The client applications are open source, allowing independent security audits, while all servers are located in Switzerland. Threema has been recommended by the Swiss army as a secure messaging alternative and is used by numerous European organizations that prioritize communication privacy. The one-time purchase model (no subscription required for personal use) aligns with Threema's philosophy of not monetizing user data.