Open Source Team Communication Platform

This open-source team communication platform offers real-time chat, video conferencing, file sharing, and integration with external services, designed as a self-hosted alternative to Slack and Microsoft Teams. Founded by Gabriel Engel in 2015, the project has over 41,000 stars as of 2026 and serves millions of users across organizations worldwide. Key features include: channels and direct messages (public and private channels, threaded conversations, direct messages, group chats, and discussion threads with mention notifications), audio and video calling (built-in WebRTC video conferencing with screen sharing, call recording, and livechat integration via Jitsi Meet), omnichannel (unified inbox consolidating email, SMS, WhatsApp, Facebook Messenger, Telegram, and web chat into a single interface for customer support), LiveChat (customer-facing chat widget with canned responses, chat routing, visitor tracking, and chatbot integration), federation (Matrix protocol support for cross-organization communication with other federated chat servers), bots and integrations (incoming and outgoing webhooks, REST API, Zapier integration, and chatbot framework with Dialogflow and IBM Watson), file sharing (drag and drop file upload with preview for images, videos, and documents, configurable file size limits and storage backends), security (end-to-end encryption for direct messages, two-factor authentication, message audit logs, and role-based access control), authentication (LDAP, Active Directory, SAML, OAuth2, and CAS integration for enterprise SSO), voice channels (persistent voice rooms with push-to-talk and always-on audio), and apps marketplace (over 100 community apps for extending functionality including polls, reminders, and workflow automation).