Open Source Alternatives to Slack

SAMA

GPL-3.0

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

Campfire

MIT

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

Cinny

AGPL-3.0

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

Element

AGPL-3.0

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

Fluxer

AGPL-3.0

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

Mattermost

Unknown

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

Mezon

Unknown

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

Nextcloud

AGPL-3.0

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

Quiet

GPL-3.0

Quiet is a peer-to-peer messaging app that syncs messages directly between devices over Tor, with no central server, no phone number required, and no metadata leaks.

Rocket.Chat

Unknown

Open source communication platform combining messaging, voice, video, and AI for organizations that need full data control, air-gapped deployments, and zero-trust security.

Stoat

Unknown

Self-hostable group chat with servers, channels, voice, and moderation tools. No ads, no data mining, built under EU privacy law.

Twake Chat

AGPL-3.0

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

Wire

GPL-3.0

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

Zulip

Apache-2.0

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

Valour

AGPL-3.0

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

Mattermost

NOASSERTION

Mattermost is an open source platform for secure collaboration across the entire software development lifecycle..

RelatedChat

Unknown

Messenger

Spacebar

AGPL-3.0

📬 Spacebar is a free open source selfhostable discord compatible communication platform

Element

AGPL-3.0

A glossy Matrix collaboration client for the web.