Threema E2EE chat app to go 'fully open source' within months

Threema follows in the footsteps of Signal and Wickr and opens its apps' codebase.
Written by Catalin Cimpanu, Contributor
Image: Threema

Secure end-to-end messaging app Threema has announced this week plans to open-source its apps' codebase to improve transparency and win over users' trust.

"Within the next months, the Threema apps will become fully open source, supporting reproducible builds," the company said in a blog post.

"This is to say that anyone will be able to independently review Threema's security and verify that the published source code corresponds to the downloaded app," the company added.

"Being advocates of the Open Source initiative (one of our founders created the m0n0wall project that went on to become the basis for many security and firewall products, both commercial and non-commercial), we have been thinking about this step for a long time," a Threema spokesperson told ZDNet in an email.

"And of course the users have often asked for it, too. Now we are in a position that allows us to go Open Source without endangering our business model and our source of income."

Threema joins Signal and Wickr

Threema, which is one of a handful of instant messaging services that support end-to-end encryption (E2EE) between users, is the third service to go open source, after Signal and Wickr.

Just like Signal and Wickr, Threema is expected to make its client-side apps source code available on GitHub.

Prior to this week's announcement, Threema has faced the regular criticism from users -- namely that they can't fully trust the app since nobody can review its code, which could easily hide encryption backdoors or other logging features.

For example, Telegram, another very popular E2EE messaging client, still faces such criticism today.

Threema's move to go open source will, without a doubt, give the app a boost in popularity. As one user explained on the HackerNews community portal this week, the announcement "is really big news" as this will put the app on the same level with Wickr as one of today's most secure E2EE messaging apps, and above Signal, which still doesn't support creating accounts without tying the user's identity to a phone number.

The company's announcement comes after it also announced last month support for E2EE video calls, another highly requested feature.

New partnership announced as well

In addition, Threema also announced a new business partner this week in German-Swiss investment company Afinum Management AG.

"The additional resources gained through this partnership enable Threema to grow beyond the German-speaking part of Europe, and we can use our energy for visionary new ideas and projects," Threema added.

Threema's current leadership structure, headed by its three original founders, has remained the same, the company said.

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