This is not proof.... I have described above what their servers do. And in the last (almost) 12 years, there has never been the slightest doubt that this is the case!

Secure Messaging Apps Comparison | Privacy Matters

This site compares secure messaging apps from a security & privacy point of view. These include Facebook Messenger, iMessage, Skype, Signal, Simple...

has updated its review of SimpleX, as you can see, SimpleX is now the highest rated application overall, the most private and the most cryptographically robust. Not that it was necessary for it to appear on this website, I have been warning about it for a long time, but in his first review in March 2024 the author of the website made an incorrect analysis of SimpleX. To highlight that it is the only one along with Signal i iMessage that have encryption resistant to quantum computation (this take it with tweezers, the explanation would be very long). The application does not collect contact information, unlike Signal and Threema, and no contact information is sent that can be associated with metadata, unlike Signal or Threema. Completely opensource server, unlike Threema which is closed. It is not dependent on any phone number, unlike Signal. View quoted note →