Best Open Source Team Chat & Messaging

Open-source platform for encrypted communication, file sharing, and collaboration based on the Matrix protocol.

Free, open-source instant messaging and VoIP platform with full Markdown support, voice/video calls, moderation tools, and self-hosting options for communities.

Cinny offers a simple, elegant, and secure interface for Matrix-based conversations, protected by end-to-end encryption.

Modern chat platform featuring text channels, community building tools, fine-grained permissions, and complete privacy protection. Open-source and ad-free.

A comprehensive collaboration platform offering end-to-end encrypted messaging, file sharing, and video calls with enterprise-grade security and compliance features.

Zulip is an open-source team chat app that uses threaded conversations to keep communication organized and efficient for teams of all sizes.

Install your own group chat system with @mentions, DMs, and mobile support. One-time purchase, no monthly fees. Includes full source code for customization.

Streamline team communication with shared inboxes, unlimited email addresses, and customizable workflows. Perfect for modern businesses seeking organized email management.

Free Matrix-based messenger with end-to-end encryption, multi-platform bridges, and on-premise deployment. Connect across 30+ networks securely.

Open-source chat solution offering real-time messaging, video calls, and file sharing for teams of all sizes.

Mattermost provides a flexible, open-source platform for secure team collaboration, designed for organizations with strict security and privacy requirements.