Open Source Communication & Collaboration Tools

Alternative toX (formerly Twitter) Premium

Decentralized social network where users own their timeline and data.

• 50,423 GitHub stars
• AGPL-3.0Licence AGPL-3.0

Alternative toCalendly

MIT self-hosted scheduling without Cal.com enterprise code

• 49,183 GitHub stars
• MITLicence MIT

Alternative toBettermode

Open source forum and community platform, self-hosted

• 47,998 GitHub stars
• GPL-2.0Licence GPL-2.0
• #Chat

Alternative toMicrosoft Teams

Self-hosted team chat with voice, video, and omnichannel support

• 46,298 GitHub stars
• MITLicence MIT
• #Chat

Alternative toChatGPT

One self-hosted interface for every AI model you use

• 46,147 GitHub stars
• MITLicence MIT
• #AI Agents

Alternative toRoam Research

Privacy-first knowledge base with outliner and graph view

• 45,303 GitHub stars
• AGPL-3.0Licence AGPL-3.0

Alternative toMuse

Personal AI agent with local memory and 100+ integrations

• 42,188 GitHub stars
• GPL-3.0Licence GPL-3.0
• #AI Agents

Alternative toKhanmigo

Agentic framework for lifelong personalized tutoring

• 41,900 GitHub stars
• Apache-2.0Licence Apache-2.0
• #AI Agents

Alternative toNotion

Team wiki and knowledge base with realtime collaboration

• 40,988 GitHub stars

Alternative toCourier

Open source notification infrastructure for product teams

• 40,175 GitHub stars
• MITLicence MIT