Open source alternatives to Pumble

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

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

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

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

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

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

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

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