Open Source Software Directory

Mastodon

> [!NOTE] > Want to learn more about Mastodon? > Click below to find out more in a video. Mastodon is a **free, open-source social network... Read More

5K stars open source

Team Chat Social Networks & Fediverse

Rocket.Chat

The ultimate secure open-source solution for team communications [Rocket.Chat](https://rocket.chat) is an open-source, secure, fully customizable commu... Read More

45.4K stars open source

Team Chat

Mattermost

# [![Mattermost logo](https://user-images.githubusercontent.com/7205829/137170381-fe86eef0-bccc-4fdd-8e92-b258884ebdd7.png)](https://mattermost.com) [Mattermost](https://mattermos... Read More

37.1K stars open source

Team Chat HR CRM & Support

AstrBot

![astrbot-github-banner-v2-light-0405_副本](https://github.com/user-attachments/assets/36fb04e4-cc75-4454-bd8b-049d11aa86f9) 简体中文｜繁體中文｜日本語｜ Français ｜ Русск... Read More

34.3K stars open source

Team Chat AI Agents

Huly

# Huly Platform [![X (formerly Twitter) Follow](https://img.shields.io/twitter/follow/huly_io?style=for-the-badge)](https://x.com/huly_io) ![GitHub License](https://img.shields.io... Read More

26.1K stars open source

Note Taking Team Chat Project Management

Zulip

# Zulip overview [Zulip](https://zulip.com) is an open-source organized team chat app with unique [topic-based threading][why-zulip] that combines the best of email and chat to ma... Read More

25.3K stars open source

Team Chat Communication

mirai

---- [![Gitter](https://badges.gitter.im/mamoe/mirai.svg)](https://gitter.im/mamoe/mirai?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge) [![MiraiForum](https:/... Read More

14.8K stars open source

Team Chat AI Agents

Tinode

# Tinode Instant Messaging Server Instant messaging full stack. Backend in pure [Go](http://golang.org) (license [GPL 3.0](http://www.gnu.org/licenses/gpl-3.0.en.html)), clients... Read More

13.3K stars open source

Team Chat

SimpleX Chat

[![build](https://github.com/simplex-chat/simplex-chat/actions/workflows/build.yml/badge.svg?branch=stable)](https://github.com/simplex-chat/simplex-chat/actions/workflows/build.ym... Read More

11.2K stars open source

Team Chat Privacy & Anonymity

Centrifugo

# Centrifugo _Scalable real-time messaging server in a language-agnostic way._ [![CI](https://github.com/centrifugal/centrifugo/actions/workflows/test.yml/badge.svg)](https://git... Read More

10.4K stars open source

Team Chat Web Servers

berty

Berty is an open, secure, offline-first, peer-to-peer and zero trust messaging app ---... Read More

9.2K stars open source

Team Chat Mobile Development

Vendicated/Vencord

# Vencord ![](https://img.shields.io/github/package-json/v/Vendicated/Vencord?style=for-the-badge&logo=github&logoColor=d3869b&label=&color=1d2021&labelColor=282828) [![Codeberg M... Read More

9K stars open source

Code Editors & IDEs Team Chat