Just from my head:
IRC, XMPP, Matrix,
SMS, RCS,
Session, SimpleX, Nostr, Jami, Tox, OnionShare, DeltaChat, Sup., GNUNet Messenger, Mumble, Zulip, Briar,
Signal, Wire, Threema,
Snapchat, Telegram, Facebook, Facebook, Facebook, Discord, Slack, iMessage, Google Chat, Twitter, KakaoTalk, WeChat, GG, TeamSpeak.
This post is not for discusson which one of standards, networks, services or garbage is the best for anything. This is a call can we just stop making more?
We don’t need to. What we need is to making things properly and ensure interoperability between those services. Think about email, it doesn’t matter what’s your provider and email client you can email anyone else. Why can’t we chat between WhatsApp and Telegram in the same way? That’s the real question that people should be asking and forcing companies into fixing.
We basically only have fully functional email because big tech wasn’t around yet to control it. We’d probably have umpteenth different versions by now if that wasn’t the case, none of which could talk to each other.