Naven
Answers
Who can see my messages on Naven?
The people in the conversation, and Naven's screening system, which reads every message before it sends. Naven is not end-to-end encrypted and does not claim to be.
This is the direct consequence of pre-send screening: a server that cannot read a message cannot check it. The trade is stated rather than hidden, and it is the reason the product exists.
What is not true is that anybody is browsing conversations. Screening is automated, and the privacy page states what is retained and for how long.
Anybody whose requirement is that the operator cannot read their messages should use Signal, which is on Naven's comparison pages.