The best open source alternative to Session is Signal. If that doesn't suit you, we've compiled a ranked list of other open source Session alternatives to help you find a suitable replacement. Other interesting open source alternatives to Session are: Cinny, Stoat, and Twake Chat.
Session alternatives are mainly Encrypted Communication Tools but may also be Team Chat & Messaging Tools or Decentralized Social Networks. Browse these if you want a narrower list of alternatives or looking for a specific functionality of Session.
Secure messaging app with state-of-the-art encryption, voice/video calls, group chats, and file sharing. No ads, trackers, or data collection.

Signal is a privacy-focused messaging application that puts security at the forefront of digital communication. Built by a nonprofit organization, this platform offers a refreshing alternative to mainstream messaging apps by prioritizing user privacy over profit.
Key Features:
Privacy-First Approach: Signal operates with a strict no-compromise policy on privacy. The app contains no advertisements, no affiliate marketing, and no tracking mechanisms. Messages and calls are encrypted by default, meaning neither Signal nor any third party can access your communications.
Independent and Sustainable: As a 501c3 nonprofit organization, Signal remains independent from major tech corporations and cannot be acquired. Development is funded through grants and user donations, ensuring the platform's mission stays aligned with user privacy rather than corporate interests.
The app uses your phone's data connection, helping you avoid SMS and MMS fees while maintaining the highest security standards in digital communication.
Looking for open source alternatives to other popular services? Check out other posts in the alternatives series and openalternative.co, a directory of open source software with filters for tags and alternatives for easy browsing and discovery.
Cinny offers a simple, elegant, and secure interface for Matrix-based conversations, protected by end-to-end encryption.

Cinny is an open-source Matrix client that provides a secure and elegant interface for seamless conversations. Built on the Matrix protocol, it offers:
Cinny is constantly evolving to create a better communication experience. As an open-source project, it benefits from community contributions and transparency.
Key features:
Whether you're looking for a secure messaging solution for personal use or team collaboration, Cinny offers a refreshing alternative to traditional chat applications. Experience the power of open-source, decentralized communication with Cinny's user-friendly approach to Matrix.
Self-hostable group chat with servers, channels, voice, and moderation tools. No ads, no data mining, built under EU privacy law.

Stoat (formerly Revolt) is a group chat app built for friends and communities who want the features of mainstream platforms without the surveillance business model behind them. It's a direct Discord alternative that covers the basics well: servers, channels, voice chat, file sharing, and markdown support, all without ads or data collection.
Built in Europe under EU data protection law, the codebase is public and the privacy policy is short enough to actually read. There's no investor pressure shaping product decisions, which means features exist because users want them, not because they serve an ad-targeting pipeline.
A few things stand out from the typical chat app:
Compared to tools like Rocket.Chat or Twake Chat, Stoat leans toward the consumer end: it's designed to feel familiar to anyone coming from mainstream chat apps, with a lighter footprint and fewer enterprise-focused features. The 20MB file upload limit and server-specific profile pictures are available without paying, which removes friction that similar platforms put behind paywalls.
The issue tracker is public and the team runs a community server, so feedback has a direct path to the people building it.
Free Matrix-based messenger with end-to-end encryption, multi-platform bridges, and on-premise deployment. Connect across 30+ networks securely.

Secure and private by design, Twake Chat leverages the Matrix protocol for decentralized communication that puts you in control. This free and open source messenger delivers enterprise-grade security with end-to-end encryption while maintaining simplicity for both work and personal use.
Key features that set Twake Chat apart:
Perfect for professional teams who need secure communication without compromising on functionality. The Matrix protocol ensures your data remains decentralized rather than controlled by a single entity, while customizable security levels let you add extra encryption when needed.
Whether you're managing team collaboration or need a reliable messaging solution that respects privacy, Twake Chat provides the security and flexibility modern organizations require.