The open-source ones? I don't even remember nowadays, because they got squished under the XMPP juggernaut. I think there was one that was based off of Gadu-Gadu

The open-source ones? I don't even remember nowadays, because they got squished under the XMPP juggernaut. I think there was one that was based off of Gadu-Gadu's protocol (may even have been basically the same protocol with just the servers switched out). But whenever someone tried to drum up support for a new open-source messenger it was always "Why not just use XMPP? It's the standard, and it's extensible, so I'm sure it can accommodate whatever features you were thinking of".