Campfire
A simple, subscription-free group chat system that you can host yourself. Includes DMs, @mentions, mobile support, and full code access for customization.
Campfire is an open-source alternative to:

Campfire is a self-hosted group chat system designed for teams who want to avoid recurring subscription fees. Built by Basecamp, it offers a familiar Slack-like interface with essential features like direct messages, @mentions, and mobile support.
Key Features
- Self-hosted: Install on your own server or cloud provider (AWS, DigitalOcean, Hetzner, etc.)
- No subscriptions: One-time setup with no ongoing fees
- Essential chat features: Rooms, DMs, @mentions, dark mode, and mobile PWA support
- Customizable: Full access to source code under MIT License for modifications
- Private rooms: Create private or public rooms for different teams or projects
- Air-gapped support: Works offline or on isolated networks
- Automatic updates: Optional daily update checks with manual override
- Chatbots: Simple HTTP API for integrating custom chatbots
Tech / Self-Hosting
- Installation: Single command via ONCE CLI (
curl https://get.once.com/campfire | sh) - System requirements: Scales from 250 users (2GB RAM, 1CPU) to 10,000 users (64GB RAM, 32CPU)
- Compatibility: Runs on laptops, local servers, or cloud infrastructure
- Mobile: Progressive Web App (PWA) with push notifications and badges
- License: MIT License (free and open source)