The best open source alternative to Campsite is Mattermost. If that doesn't suit you, we've compiled a ranked list of other open source Campsite alternatives to help you find a suitable replacement. Other interesting open source alternatives to Campsite are: Zulip, Campfire, and Wire.
Campsite alternatives are mainly Team Chat & Messaging Tools but may also be Encrypted Communication Tools or Collaborative Workspaces. Browse these if you want a narrower list of alternatives or looking for a specific functionality of Campsite.
Mattermost provides a flexible, open-source platform for secure team collaboration, designed for organizations with strict security and privacy requirements.

Mattermost is an open-source collaboration platform built for organizations that require high levels of privacy, security and control over their communications. Some key features and benefits include:
Mattermost is designed for industries like defense, government, financial services, and critical infrastructure that have stringent requirements around data sovereignty and security. It provides a self-hosted alternative to cloud-based tools, giving organizations complete control over their collaboration environment.
The platform aims to improve team productivity and accelerate mission-critical work by providing a centralized hub for communication, process management, and integrations. With its focus on security and flexibility, Mattermost enables organizations to collaborate effectively even in highly regulated or air-gapped environments.
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.
Zulip is an open-source team chat app that uses threaded conversations to keep communication organized and efficient for teams of all sizes.

Zulip is a powerful, open-source team chat application designed to revolutionize how distributed teams communicate. Unlike traditional chat tools that can feel chaotic and stressful, Zulip's unique threading model organizes conversations by topic, making it easy to manage multiple workstreams and stay on top of important discussions.
Key features and benefits:
Threaded Conversations: Zulip's core feature is its topic-based threading, which allows teams to have multiple conversations simultaneously without losing context or creating confusion.
Efficient Communication: The organized structure helps team members quickly catch up on relevant discussions and reduces information overload.
Flexible Deployment: Choose between Zulip Cloud for convenience or self-host the 100% open-source software for ultimate control and compliance.
Cross-Platform Support: Access Zulip from desktop and mobile apps, ensuring seamless communication across devices.
Rich Integrations: Connect Zulip with your favorite tools and services to streamline workflows.
Powerful Search: Easily find past conversations and shared knowledge with Zulip's robust search functionality.
Open Source: Benefit from a transparent, community-driven development process and the ability to customize the platform to your needs.
Zulip is ideal for various use cases:
With its focus on organized communication, Zulip empowers teams to work more efficiently, make decisions faster, and create a searchable knowledge repository as a natural byproduct of their conversations. Whether you're managing a small team or coordinating thousands of contributors, Zulip provides the structure and flexibility needed to succeed in today's distributed work environment.
Install your own group chat system with @mentions, DMs, and mobile support. One-time purchase, no monthly fees. Includes full source code for customization.

Break free from endless subscription fees with this self-hosted group chat solution that puts you in complete control. If you've used Slack or Teams, you already know how to use Campfire - but without the monthly charges that never end.
Key features include:
Perfect for multiple use cases:
Technical advantages:
You get the complete Rails source code, allowing full customization for your specific needs. One-time purchase, no recurring fees - own your chat system and your data forever.
A comprehensive collaboration platform offering end-to-end encrypted messaging, file sharing, and video calls with enterprise-grade security and compliance features.

Wire delivers military-grade security without sacrificing user experience. The platform features always-on end-to-end encryption for messages, files, and calls, while maintaining an intuitive interface for seamless team collaboration.
Key capabilities include:
Trusted by industry leaders including BMW, ExxonMobil, and government organizations worldwide, Wire ensures your sensitive communications remain private and compliant. The platform is particularly valuable for organizations requiring: