Zulip
Zulip is a powerful, open source group chat application.
Tinode
Instant messaging platform.
Element
Fully-featured Matrix client for Web, iOS & Android.
SimpleX Chat
The most private and secure chat and applications platform - now with double ratchet E2E encryption.
Mumble
Low-latency, high quality voice/text chat software.
Synapse
Server for [Matrix](https://matrix.org/), an open standard for decentralized persistent communication.
Tox
Distributed, secure messenger with audio and video chat capabilities.
Stoat
Stoat is a user-first chat platform built with modern web technologies.
Chitchatter
Peer-to-peer chat app that is serverless, decentralized, and ephemeral.
Live Helper Chat
Live Support chat for your website.
RetroShare
Secured and decentralized communication system.
Hyphanet
Anonymously share files, browse and publish _freesites_ (web sites accessible only through Hyphanet) and ch…
Notifo
Multichannel notification server with support for Email, Mobile Push, Web Push, SMS, messaging and a javasc…
OTS
One-Time-Secret sharing platform with a symmetric 256bit AES encryption in the browser.
Spectrum 2
Spectrum 2 is an open source instant messaging transport.
Shhh
Keep secrets out of emails or chat logs, share them using secure links with passphrase and expiration dates.
PushBits
Notification server for relaying push notifications via Matrix, similar to PushBullet and Gotify.