https://simplex.chat/

"No user identifier"

So how am I supposed to know that I'm talking to the person I think I'm talking to? Ask them who their first-grade teacher was and the name of their first pet?

Hmm.

https://github.com/simplex-chat/simplex-chat/blob/stable/docs/SIMPLEX.md#the-best-protection-against-spam-and-abuse

"you cannot be contacted unless you share a one-time invitation link or an optional temporary user address"

But later in that same document:

"The proposed design, unlike most P2P networks, has no global user identifiers of any kind, even temporary."

Not sure I'm on board with this one.