Slack

Rocket.Chat

Open-source chat solution offering real-time messaging, video calls, and file sharing for teams of all sizes.

Mattermost

Mattermost provides a flexible, open-source platform for secure team collaboration, designed for organizations with strict security and privacy requirements.

Zulip

Zulip is an open-source team chat app that uses threaded conversations to keep communication organized and efficient for teams of all sizes.

Nextcloud

Nextcloud offers on-premises file sync, sharing and collaboration platform with advanced security and privacy features.

Chatwoot

An open-source customer engagement platform that unifies multiple channels, enabling businesses to provide seamless support and build lasting relationships.

Element

Open-source platform for encrypted communication, file sharing, and collaboration based on the Matrix protocol.

Huly

An open-source platform that combines project management, team communication, document collaboration, and virtual office spaces in one integrated solution.

Colanode

Collaboration suite with real-time messaging, rich text pages, file management, and dynamic databases - built for offline work (alternative to Slack, Notion)

Cinny

Cinny offers a simple, elegant, and secure interface for Matrix-based conversations, protected by end-to-end encryption.

Wire

A comprehensive collaboration platform offering end-to-end encrypted messaging, file sharing, and video calls with enterprise-grade security and compliance features.

Movim

Movim centralizes all your communications in one place.

SAMA

Open source chat server with end-to-end encryption, clustering support, and comprehensive messaging features for building real-time communication apps

Stoat

Modern chat platform featuring text channels, community building tools, fine-grained permissions, and complete privacy protection. Open-source and ad-free.

Revolt

Repository for miscellaneous repository management and discussions: https://github.com/revoltchat/revolt/discussions

Twake

Twake is a secure open source collaboration platform to improve organizational productivity.

Fluxer

Free, open-source instant messaging and VoIP platform with full Markdown support, voice/video calls, moderation tools, and self-hosting options for communities.

Spacebar

RelatedChat

Campfire

Install your own group chat system with @mentions, DMs, and mobile support. One-time purchase, no monthly fees. Includes full source code for customization.

Mezon

Build your own community space for gaming, chatting, and hanging out with friends worldwide. Customize your environment for the perfect social experience.

Valour

Open-source communication platform with multi-window chat, economy systems, and privacy-first approach. Built by communities for superior performance.

Twake Chat

Free Matrix-based messenger with end-to-end encryption, multi-platform bridges, and on-premise deployment. Connect across 30+ networks securely.

Virola Messenger