Communications platform that puts data protection first (alternative to Gitter.im and Slack).
Self-hostedOpen sourceCommunication - Custom Communication Systems
46,343MITNodejsupdated Oct 2026
Notification infrastructure for developers.
Self-hostedOpen sourceCommunication - Custom Communication Systems
40,214MITNodejsupdated Oct 2026
Platform for secure collaboration across the entire software development lifecycle, can be integrated with Gitlab (alternative to Slack).
Self-hostedFreeCommunication - Custom Communication Systems
39,454ProprietaryGoupdated Oct 2026
Customer communication platform (alternative to Intercom and Zendesk).
Self-hostedFreeCommunication - Custom Communication Systems
38,453ProprietaryRubyupdated Oct 2026
Push notifications to phone or desktop using HTTP PUT/POST, with Android app, CLI and web app, similar to Pushover and Gotify.
Self-hostedOpen sourceCommunication - Custom Communication Systems
35,117Apache-2.0Goupdated Oct 2026
Zulip is a powerful, open source group chat application.
Self-hostedOpen sourceCommunication - Custom Communication Systems
26,125Apache-2.0Pythonupdated Oct 2026
The most private and secure chat and applications platform - now with double ratchet E2E encryption.
Self-hostedOpen sourceCommunication - Custom Communication Systems
19,605AGPL-3.0Haskellupdated Oct 2026
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.
Self-hostedOpen sourceCommunication - Custom Communication Systems
17,655MITPythonupdated Oct 2026
WhatsApp API gateway exposing messaging as REST endpoints, with a web dashboard, multi-account sessions, and webhook events (alternative to WhatsApp Business API providers).
Self-hostedOpen sourceCommunication - Custom Communication Systems
16,317MITDockerupdated Oct 2026
Notification server with Android and CLI clients (alternative to PushBullet).
Self-hostedOpen sourceCommunication - Custom Communication Systems
16,136MITGoupdated Oct 2026
Fully-featured Matrix client for Web, iOS & Android.
Self-hostedOpen sourceCommunication - Custom Communication Systems
13,619Apache-2.0Nodejsupdated Oct 2026
T
Instant messaging platform. Backend in Go. Clients: Swift iOS, Java Android, JS webapp, scriptable command line; chatbots.
Self-hostedOpen sourceCommunication - Custom Communication Systems
13,540GPL-3.0Goupdated Sept 2026
C
Language-agnostic real-time messaging (Websocket or SockJS) server.
Self-hostedOpen sourceCommunication - Custom Communication Systems
10,926MITGoupdated Oct 2026
S
Screego is a simple tool to quickly share your screen to one or multiple people via web browser.
Self-hostedOpen sourceCommunication - Custom Communication Systems
10,741GPL-3.0Goupdated Oct 2026
Instant messaging and VoIP platform built for friends, groups, and communities (alternative to Discord).
Self-hostedOpen sourceCommunication - Custom Communication Systems
10,686AGPL-3.0Dockerupdated Oct 2026
Conversational app builder (alternative to Typeform and Landbot).
Self-hostedOpen sourceCommunication - Custom Communication Systems
10,583AGPL-3.0Dockerupdated Oct 2026
Low-latency, high quality voice/text chat software.
Self-hostedOpen sourceCommunication - Custom Communication Systems
8,369BSD-3-ClauseC++updated Oct 2026
Virtual office / virtual conference application presented as a 16-bit RPG video game.
Self-hostedOpen sourceCommunication - Custom Communication Systems
5,888AGPL-3.0Dockerupdated Oct 2026
Server for [Matrix](https://matrix.org/), an open standard for decentralized persistent communication.
Self-hostedOpen sourceCommunication - Custom Communication Systems
4,738Apache-2.0Pythonupdated Oct 2026
O
Share sensitive information securely with self-destructing links that are only viewable once.
Self-hostedOpen sourceCommunication - Custom Communication Systems
2,977MITRubyupdated Oct 2026
T
High-performance and feature-rich chat server for Matrix, and the successor to conduwuit (fork of Conduit).
Self-hostedOpen sourceCommunication - Custom Communication Systems
2,700Apache-2.0Rustupdated Oct 2026
T
Distributed, secure messenger with audio and video chat capabilities.
Self-hostedOpen sourceCommunication - Custom Communication Systems
2,696GPL-3.0Cupdated Oct 2026
Stoat is a user-first chat platform built with modern web technologies.
Self-hostedOpen sourceCommunication - Custom Communication Systems
2,679AGPL-3.0Rustupdated Oct 2026
Web Whiteboard to collaborate in real-time on schemas, drawings, and notes.
Self-hostedOpen sourceCommunication - Custom Communication Systems
2,674AGPL-3.0Nodejsupdated Oct 2026
Realtime server for reliable two-way communication over WebSockets, Server-sent events, etc.
Self-hostedOpen sourceCommunication - Custom Communication Systems
2,389MITGoupdated Oct 2026
Peer-to-peer chat app that is serverless, decentralized, and ephemeral.
Self-hostedOpen sourceCommunication - Custom Communication Systems
2,343GPL-2.0Nodejsupdated Oct 2026
L
Live Support chat for your website.
Self-hostedOpen sourceCommunication - Custom Communication Systems
2,247Apache-2.0PHPupdated Oct 2026
R
Secured and decentralized communication system. Offers decentralized chat, forums, messaging, file transfer.
Self-hostedOpen sourceCommunication - Custom Communication Systems
2,021GPL-2.0C++updated Oct 2026
Whistleblowing software enabling anyone to easily set up and maintain a secure reporting platform.
Self-hostedOpen sourceCommunication - Custom Communication Systems
1,525AGPL-3.0Pythonupdated Oct 2026
Federated, end-to-end encrypted messaging service for the web, iOS, and Android, supporting text, photos, video, and WebRTC video and audio calls.
Self-hostedOpen sourceCommunication - Custom Communication Systems
1,504Apache-2.0Dockerupdated Jun 2026