xmpp

Instant messaging platform. Backend in Go. Clients: Swift iOS, Java Android, JS webapp, scriptable command line; chatbots

bridge between mattermost, IRC, gitter, xmpp, slack, discord, telegram, rocketchat, twitch, ssh-chat, zulip, whatsapp, keybase, matrix, microsoft teams, nextcloud, mumble, vk and more with REST API (mattermost not required!)

Jitsi is an audio/video and chat communicator that supports protocols such as SIP, XMPP/Jabber, IRC and many other useful features.

Movim - Decentralized social platform

SDK monorepo for Ethora chat / messaging platform. (1) Pick an SDK for your frontend stack. (2) Integrate manually or using ethora-setup. (3) Optionally configure app settings, deploy AI agents etc. Server: ethora.com cloud [free]. Dedicated server + SLA option for enterprise customers.