Searching for a secure, community-driven alternative to Slack? Our selection of open-source communication platforms empowers you with full transparency, customizable deployments, and enterprise-grade features, so you can ditch vendor lock-in, audit every line of code, and adapt your collaboration tools to match your organization’s exact requirements.
Rocket.Chat
Rocket.Chat is a free and open-source communications platform designed for organizations that prioritize data protection and operational control.
Trusted by global institutions such as Deutsche Bahn, the US Navy, and Credit Suisse, Rocket.Chat offers customizable messaging, voice, video, and AI-powered tools to support critical operations in highly secure environments.
With deployment options ranging from on-premise and air-gapped to secure cloud, the platform ensures resilience and continuity, even under extreme conditions. Its adherence to a zero-trust security model and authorization for classified networks up to IL6 demonstrates its battle-tested reliability.
Rocket.Chat empowers organizations with complete control over their data, offering self-hosted options, end-to-end encryption, audit logs, and fine-tuned retention policies. By consolidating communication modes and supporting federated collaboration, it removes silos and enhances mission clarity.
Integrated automation and AI streamline workflows and improve responsiveness, while a flexible, extensible architecture and no vendor lock-in encourage innovation and adaptability. Rocket.Chat delivers secure, scalable communication, on your terms.
Mattermost
Mattermost is a secure, open-source collaboration platform built to support the complex demands of modern software development and mission-critical operations.
Designed with transparency and adaptability at its core, Mattermost gives organizations full control over their communications, whether deployed in secure cloud, on-premise, or air-gapped environments. Written in Go and React, and released under the MIT license, it combines technical reliability with the freedom to customize and innovate.
With support for deep integrations, native audio calls, built-in playbooks, and seamless extensibility, Mattermost delivers clarity and coordination in high-pressure environments.
Its robust security framework includes identity and access controls, compliance features, and detailed auditing to meet stringent regulations such as GDPR, HIPAA, and FINRA.
Trusted by entities like the U.S. Navy, Mattermost is resilient by design, supporting high-availability deployments and ensuring communication continuity even in the most constrained settings. It’s more than a messaging tool, it’s a mission-ready platform engineered to evolve with your organization’s needs.
Zulip
Zulip is a powerful, open-source team chat application that revolutionizes the way teams communicate by offering a unique topic-based threading model.
This structure provides clarity and organization, making it easier to manage conversations across time zones or large, simultaneous discussions.
Unlike traditional messaging apps, Zulip supports asynchronous work, ensuring that teams can focus on one conversation at a time without losing track of others.
With over 1,000 contributors and more than 500 commits each month, Zulip is the largest and fastest-growing open-source team chat project.
It also serves as a living knowledge base, naturally organizing your team’s discussions and institutional memory. Zulip's intuitive UI makes managing numerous workstreams easier than with other tools like Slack.
Available as both a cloud solution and a self-hosted option, Zulip gives teams complete control over their data. Its seamless migration tools make transitioning from platforms like Slack simple.
If your team seeks a more efficient, organized way to communicate, Zulip offers a powerful alternative.
Huly
Huly is an open-source platform designed to streamline business application management, including CRM systems. It combines various tools such as Chat, Project Management, CRM, HRM, and ATS into a single platform, making it a comprehensive solution for teams looking to improve collaboration and productivity. Whether you're a developer, product manager, or part of a remote team, Huly’s features support seamless project tracking and communication, including the option for self-hosting for those who want full control over their data.
Huly offers an easy-to-use Docker setup through the huly-selfhost project, allowing users to quickly self-host the platform without a steep learning curve. The Team Planner enables teams to manage tasks by viewing them in a centralized team calendar, ensuring alignment on deadlines and responsibilities. Real-time notifications keep teams updated on project changes, while time-blocking helps individuals organize their daily tasks and maintain productivity.
The customizable Virtual Office allows teams to collaborate remotely through audio and video calls, eliminating the need for additional software. GitHub integration provides bidirectional synchronization for managing tasks and tracking issues within the Huly platform. Teams can organize multiple repositories, migrate milestones across projects, and track progress all in one place.
Huly’s MetaBrain serves as a knowledge base for teams, connecting tasks, notes, and documents to improve workflow. The document management system supports real-time collaboration, with features such as rich text formatting, multimedia integration, and task management. Teams can link documents to GitHub issues, assign tasks, and keep track of updates effortlessly. Advanced search and filtering ensure that finding relevant information is fast and efficient.
Huly replaces multiple tools with one platform, offering features for project management, task tracking, real-time collaboration, and GitHub integration. With its customizable virtual office and AI-powered knowledge base, Huly enhances team collaboration and productivity, making it an ideal choice for modern teams looking to streamline their workflows.
Experience Huly for free and see how it can transform your team's workflow.
Element
Be in your Element with Secure, Sovereign Communication
In an age where digital collaboration is essential, Element promises communication on your terms. It goes beyond being just a messaging app, it's a platform built by the original creators of Matrix, an open communication standard. Element began as Vector and later Riot, but its mission has remained the same: to provide users full control over their communications. Now, as Element, it offers a secure, compliant, and highly customizable environment for businesses and communities.
Element is engineered for security and compliance, ensuring that your conversations remain private, tamper-proof, and fully under your control. Built on the Matrix JS SDK, the platform allows for end-to-end encrypted communication, prioritizing privacy at all times.
Unlike conventional platforms that lock your data behind proprietary walls, Element gives you the freedom to choose how and where your data is hosted. It's open source, so you can opt for self-hosting or a managed solution through the Element Server Suite. With customizable network configurations and permission settings, you can build an environment that meets your organization’s needs.
Element facilitates real-time collaboration across departments, teams, and even companies. Whether for a quick chat or a large-scale collaboration, Element ensures seamless communication. The frontend, the Element app, offers an intuitive interface, while the backend architecture can be tailored to your existing infrastructure.
Matrix, the open standard, powers Element. It defines how data is stored, synchronized, and federated, ensuring your communication setup is interoperable, future-proof, and extensible. You’re not tied to one vendor or stack, you’re building on a protocol that adapts as your needs evolve.
Element is more than just a messaging tool. It’s about fostering trust through communication. Whether supporting mission-critical business operations or enabling secure conversations across borders, Element provides the tools you need to collaborate confidently and independently.
Stay sovereign. Stay secure. Be in your Element.