we talk here

currently there's a few

Stoat/Revolt: https://stoat.chat

Fluxer: https://fluxer.app/

Spacebar: https://spacebar.chat/

Matrix: https://element.io/en

Root: https://www.rootapp.com/

Teamspeak: https://www.teamspeak.com/en/

Spacebar and Fluxer are open sourced and just started out, there isn't a lot polished with it yet.

Matrix is open sourced and it's federalized. you can make your own server and such. example is Bsky being a fork of Mastodon.

Root is venture capital backed, it's backed by investors. If this gets popular then the same of what happened to Discord will happen to Root.

Stoat is open source, centralized.