Instant Messaging

Real-time Text Transmission via Internet


More trustworthy than instant messengers from American or Chinese companies is Threema from Switzerland.
This messenger does not require any personal data! The Threema ID generated locally on your device is sufficient!

  • no registration with name, address or telephone number
  • no SIM card required (works in a tablet without 4G/5G modem)
  • Threema meets the requirements of the EU-GDPR
  • Threema is approved for young people under 16 years of age

With Threema, you can chat and make phone calls with end-to-end encryption (optionally also with video, i.e. videophone).

Simple User Interface

The ease of use also speaks for Threema: chatting works just like with other messaging services. The app is not overloaded and only has what you really need.

Privacy by Design

The developers' restriction to the absolute essentials not only ensures easy usability for the user through tidy design. It also helps the developers to keep the programme code lean and clear. The motto is “Privacy by Design”.

You cannot show your friends your status (state of mind, greeting, statement) in real time and the recipient circle is also not told what music you are listening to.

But the sending status of the messages (delivered/read) is reliably transmitted (can be switched off). For most of us, this is much more important than knowing what music, audio books or videos are currently playing on our friend's phone or what he/she is currently thinking.
If you want to know the latter, that's a reason to start a chat – or a non-interceptable phone call with Threema. Augenzwinkern
And if you want to send pictures to each other, you can do so very conveniently with any smartphone using the “Share” function.

Messengers are criticised when they cannot send large videos.
Videos can be wonderful Trojan slingshots!
This makes the use of a secure messenger absurd!

27.12.2022: Threema further aligns the messenger versions for Android and iOS. Some functions that were previously only available for the Android version are now also available to iOS users. This also includes PFS.

Threema Apps are Open Source

Since 21.12.2020, Threema has published the source code of its apps, i.e. the apps are now “open source”. This allows interested experts to conduct independent security audits at any time. In addition, external experts are regularly entrusted with subjecting Threema to comprehensive audits.

The source code of the server version is not disclosed. Threema considers the server source code to be the basis of its business and therefore does not want to publish it. Otherwise, anyone could copy the service and endanger Threema's business model as a competitor.

However, it is not a real disadvantage that Threema's server software is not open source. Thanks to “Security and Privacy by Design” without a central user account with decentralised storage of customer data exclusively on customer devices, Threema's servers only serve as relay stations anyway.

As an example of someone using source code for their own messaging service and competing with the original service, consider Wire.
Wire uses the Signal protocol (formerly Axolotl protocol) and was a German-Swiss company before their headquarters moved to San Francisco.

Reference Customers

Over seven thousand companies use Threema Work, including: ADAC, Bosch, Daimler, Rossmann, Erasmus University Rotterdam, Kantonsspital Winterthur, thyssenkrupp.

Threema is also used by the Swiss Federal Administration up to the level of the Federal Councillors for confidential communication.

As a Frankfurt resident, I am pleased that the city of Frankfurt am Main is also one of the customers: Threema Work is used in the following offices, among others: Central IT Office, Education, Fire Department, Public Health Office, City Drainage, Road Construction Office, Public Order Office, Parks and Recreation Office.


Finding and Exploiting Vulnerabilities in H.264 Decoders

Mike Kuketz: Messenger: Threema-Client nun Open-Source (German)

Threema: Clients and Success Stories – Threema Work

Threema: Information and graphics for press purposes

Cure53: Pentest & Audit Report Threema Mobile Apps 10.2020 (PDF)

TWiT Tech Podcast Network: Threema Goes Open-Source

back | Session | Signal | App review: Threema | Text auf Deutsch

Keyword list: 4G, Android, Apps, Books, Chat, Client, End-to-end encryption, H.264, IT, Instant Messaging, Internet, Mobile Apps, Modem, Network, Open Source, PDF, PFS, Privacy, SIM, Server, Service, Services, Smartphone, Software, Storage, Stories, Threema, User, report, review

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