Rocket.Chat

Rocket.Chat is an open-source team communications platform — essentially a self-hosted alternative to Slack or Microsoft Teams that organizations can run on their own servers rather than relying on a third-party cloud service. The problem it solves is that many organizations, especially in government, defense, finance, or healthcare, need real-time messaging and collaboration tools but cannot or will not send their internal communications through an external company's infrastructure. Rocket.Chat gives those organizations all the features of a modern chat platform while keeping full control over their data.

The platform supports text channels, direct messages, voice and video calls, file sharing, and end-to-end encryption. It can federate with other Rocket.Chat instances, meaning separate organizations can communicate with each other securely across a network. Admins can install apps from a marketplace or build custom integrations using the Apps-Engine framework, which lets developers extend the platform's capabilities similarly to how Slack allows custom bots and apps. Users can access Rocket.Chat through a web browser, desktop apps (Windows, Mac, Linux), or mobile apps (iOS and Android).

You would use Rocket.Chat when your organization needs a professional messaging tool but requires self-hosting for compliance, security policy, or air-gapped network reasons. It can be deployed using Docker, Kubernetes, or managed cloud hosting. The codebase is written in TypeScript, originally built on the Meteor framework for its real-time capabilities, and runs on Node.js. The license is MIT, making it free to use, modify, and deploy.