Open-source startups in Communication

Your self-hosted, globally interconnected microblogging community

A platform for community discussion. Free, open, simple.

The Secure CommsOS™ for mission-critical operations

The open-source communication infrastructure for agents and products

Mattermost is an open source platform for secure collaboration across the entire software development lifecycle..

Send push notifications to your phone or desktop using PUT/POST

Telegram Desktop messaging app

Jitsi Meet - Secure, Simple and Scalable Video Conferences that you use as a standalone app or embed in your web application.

Telegram for Android source

A private messenger for Android.

Hey is a decentralized and permissionless social media app built with Lens Protocol 🌿

Zulip server and web application. Open-source team chat that helps teams stay productive and focused.

:love_letter: An extensible desktop mail app built on the modern web. Forks welcome!

Ready-to-use Media-over-QUIC / SRT / WebRTC / RTSP / RTMP / LL-HLS / MPEG-TS / RTP live media server and media proxy that allows to read, publish, proxy, record and playback real-time video and audio streams.

SimpleX - the first messaging network operating without user identifiers of any kind - 100% private by design! iOS, Android and desktop apps 📱!

Production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running inside a container.

The Bluesky Social application for Web, iOS, and Android

:love_letter: A beautiful, fast and fully open source mail client for Mac, Windows and Linux.

📮 A fully featured open source mail delivery platform for incoming & outgoing e-mail

IM Chat OpenClaw

A private messenger for Windows, macOS, and Linux.

Simple forum software for building great communities.

A simple server for sending and receiving messages in real-time per WebSocket. (Includes a sleek web-ui)

Mail-in-a-Box helps individuals take back control of their email by defining a one-click, easy-to-deploy SMTP+everything else server: a mail server in a box.

Node.js based forum software built for the modern web

All-in-one Mail & Collaboration server. Secure, scalable and fluent in every protocol (IMAP, JMAP, SMTP, CalDAV, CardDAV, WebDAV).

🐀 A decentralised discussion platform for communities.

Alternative Twitter front-end

A Cloudflare-based email service | 基于 Cloudflare 的邮箱服务 | Cloudflare Email 邮箱 Mail

Thunderbird for Android – Open Source Email App for Android (fka K-9 Mail)

A privacy-aware, distributed, open source social network.

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

A glossy Matrix collaboration client for the web.

mailcow: dockerized - 🐮 + 🐋 = 💕

A private messenger for iOS.

A commenting system powered by GitHub Discussions. :octocat: :speech_balloon: :gem:

Synapse: Matrix homeserver written in Python/Twisted.

🌎 A completely free and open interplanetary-microblogging platform 🚀

Server supporting the Signal Private Messenger applications on Android, Desktop, and iOS

screen sharing for developers https://screego.net/

A free and open source instant messaging and VoIP chat app built for friends, groups, and communities.

live video streaming server in golang