Threema

Threema is a Swiss company that develops and operates the secure messaging app of the same name. Security and privacy have been at the heart of their mission from the very beginning.

To ensure full transparency, Threema’s source code is publicly available and can be independently verified using Reproducible Builds where possible (currently on Android).

This commitment to transparency extends to encryption: Threema relies on proven, publicly documented cryptography based on open-source technology. All messages, calls, and files are end-to-end encrypted. Additionally, the app undergoes regular security audits and penetration tests conducted by recognized security experts.

Furthermore, Threema adheres to Privacy by Design principles and generates as little metadata as possible, as a reduced data footprint results in a smaller attack surface. Neither a phone number nor an email address is required to use the app. Contact lists and groups are managed directly on the device, and messages are deleted from the Threema server in Switzerland immediately upon delivery.

Alongside the Threema app for private users, the company offers Threema Work and Threema OnPrem, which are specifically designed for confidential communication within businesses and government agencies.

Threema is a Swiss instant messenger that was built from the ground up with security and data privacy in mind.

For one thing, state-of-the-art end-to-end encryption prevents anyone other than the intended recipient (including the service provider) from reading the messages users exchange. For another thing, it is not required to provide any personal information (such as a phone number or email address) to use Threema. In other words, the service can be used completely anonymously. Finally, Threema adheres to the Privacy by Design principles, which is to say that only as little metadata as possible is generated, and it is only stored for the shortest amount of time possible.

The service provider hosts its own servers in Switzerland.