Best Open Source Encrypted Communication

Open source chat server with end-to-end encryption, clustering support, and comprehensive messaging features for building real-time communication apps

Tuta offers encrypted email, calendar and contacts with quantum-resistant security, protecting your privacy without ads or tracking.

Secure messaging app with state-of-the-art encryption, voice/video calls, group chats, and file sharing. No ads, trackers, or data collection.

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.

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