Apprise
Apprise allows you to send a notification to almost all of the most popular notification services available to us today such as: Telegram, Discord, Slack, Amazon SNS, Gotify, etc.
Centrifugo
Language-agnostic real-time messaging (Websocket or SockJS) server.
Chatwoot
Self-hosted customer communication platform (alternative to Intercom & Zendesk).
Chitchatter
A peer-to-peer chat app that is serverless, decentralized, and ephemeral.
Conduit
A simple, fast, and reliable chat server powered by Matrix.
Dendrite
Second-generation Matrix homeserver written in Go. It intends to provide an efficient, reliable and scalable alternative to Synapse.
Databag
Federated, end-to-end encrypted messaging service for the web, iOS, and Android, supporting text, photos, video, and WebRTC video and audio calls.
Darkwire.io
End-to-end encrypted instant web chat.
Element
Fully-featured Matrix client for Web, iOS & Android.
GNUnet
Free software framework for decentralized, peer-to-peer networking.
Gotify
Self-hosted notification server with Android and CLI clients, similar to PushBullet.
Hawkpost
HawkPost is a web app that lets you create unique links that you can share with a person that desires to send you important information but doesn’t know how to encrypt it. The message is encrypted in their browser and sent to your email address.
Hyphanet
Anonymously share files, browse and publish (web sites accessible only through Hyphanet) and chat on forums.
Jami
Free and universal communication platform which preserves the user’s privacy and freedoms (formerly GNU Ring).
KChat
PHP Based Live Chat Application.
LeapChat
Ephemeral, encrypted, in-browser chat rooms.
Live Helper Chat
Live Support chat for your website.
Mattermost
Platform for secure collaboration across the entire software development lifecycle, can be integrated with Gitlab (alternative to Slack).
Mibew
Mibew Messenger is an open-source live support application written in PHP and MySQL. It enables one-on-one chat assistance in real-time directly from your website.
MiAOU
Multi-room persistent chat server.
Mumble
Low-latency, high quality voice/text chat software.
ntfy
Push notifications to phone or desktop using HTTP PUT/POST, with Android app, CLI and web app, similar to Pushover and Gotify.
Novu
Self-hosted / cloud notification infrastructure for developers.
Notifo
Multichannel notification server with support for Email, Mobile Push, Web Push, SMS, messaging and a javascript plugin.
OTS
One-Time-Secret sharing platform with a symmetric 256bit AES encryption in the browser.
PushBits
Self-hosted notification server for relaying push notifications via Matrix, similar to PushBullet and Gotify.
RetroShare
Secured and decentralized communication system. Offers decentralized chat, forums, messaging, file transfer.
Revolt
Revolt is a user-first chat platform built with modern web technologies.
Rocket.Chat
Teamchat solution similar to Gitter.im or Slack.
Screego
Screego is a simple tool to quickly share your screen to one or multiple people via web browser.
Shhh
Keep secrets out of emails or chat logs, share them using secure links with passphrase and expiration dates.
SimpleX Chat
The most private and secure chat and applications platform - now with double ratchet E2E encryption.
Soketi
Simple, fast, and resilient open-source WebSockets server (drop-in alternative to Pusher).
Spectrum 2
Spectrum 2 is an open source instant messaging transport. It allows users to chat together even when they are using different IM networks.
Tailchat
Next generation noIM application in your own workspace, not only another Slack/Discord/rocket.chat.
Synapse
Server for , an open standard for decentralized persistent communication.
Syndie
Syndie is a libre system for operating distributed forums.
TextBelt
Outgoing SMS API that uses carrier-specific gateways to deliver your text messages for free, and without ads.
Tiledesk
All-in-one customer engagement platform from lead-gen to post-sales, from WhatsApp to your website. With omni-channel live agents and AI-powered chatbots (alternative to Intercom, Zendesk, Tawk.to and Tidio).
Tinode
Instant messaging platform. Backend in Go. Clients: Swift iOS, Java Android, JS webapp, scriptable command line; chatbots.
Tox
Distributed, secure messenger with audio and video chat capabilities.
Typebot
Conversational app builder (alternative to Typeform or Landbot).
WBO
Web Whiteboard to collaborate in real-time on schemas, drawings, and notes.
Yopass
Secure sharing of secrets, passwords and files.
Zulip
Zulip is a powerful, open source group chat application.