Manyverse - A social network off the grid
Public - Group chats.
chitchat - Chat Room with Selfies and Pagers (yes, pagers!)
Wire - Private & Secure Messenger
Slack - A messaging app for teams who see through the Earth!
Mastodon - Mastodon is a decentralized, open source social network. This is just one part of the network, run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome!