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The Best Open-Source Alternatives to Google Chat

Are you looking for a free or self-hosted alternative to Google Chat? In 2026, avoiding expensive proprietary software subscriptions is easier than ever. The open-source community has built excellent privacy-friendly tools within the Team Communication ecosystem. Currently, there are 6 active replacements available, with Mastodon being one of the most prominent selections.

Quick Comparison: Google Chat vs. Open Source

Full comparison: Google Chat vs. Mastodon →
CriteriaGoogle ChatOSS Replacements
Pricing modelPaid / Monthly Fees100% Free / Self-Hosted
Data ControlThird-party ServersFull Ownership & Privacy
CustomizabilityRestricted by VendorUnlimited (Modify Codebase)

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Mastodon

šŸ“ˆ Trending⭐ 10k+ Stars
AGPL-3.0

Mastodon is a decentralized, open-source social media platform enabling individuals to host and interact with their own communities, providing a powerful alternative to traditional chat and messaging services like Google Chat. By hosting your own instance, users maintain full control over their data, enhancing online privacy and security while fostering a more community-driven experience.

⭐ 50,195 Stars
šŸ“ 7,483 Forks
ā— 0 Open Issues
šŸ·ļø AGPL-3.0

Rocket.Chat

šŸ“ˆ Trending⭐ 10k+ Stars
NOASSERTION

Rocket.Chat is a highly customizable, open-source communication platform that enables secure team collaboration through real-time messaging, file sharing, and screen sharing, serving as a private and flexible alternative to commercial messaging solutions like Google Chat.

⭐ 45,887 Stars
šŸ“ 13,756 Forks
ā— 0 Open Issues
šŸ·ļø NOASSERTION

Mattermost

šŸ“ˆ Trending⭐ 10k+ Stars
NOASSERTION

Mattermost is a secure, self-hosted team communication platform that provides a feature-rich alternative to Google Chat, enabling teams to collaborate and communicate with end-to-end encryption and complete control over their data. As a highly customizable and scalable open-source solution, Mattermost empowers users to maintain their privacy and data sovereignty without sacrificing functionality.

⭐ 38,620 Stars
šŸ“ 8,869 Forks
ā— 0 Open Issues
šŸ·ļø NOASSERTION

Zulip

šŸ“ˆ Trending⭐ 10k+ Stars
Apache-2.0

Zulip is a powerful, open-source team chat platform that fosters organized discussions, topic-based threading, and flexible notification controls, making it an ideal alternative to Google Chat for teams prioritizing ease-of-use and data sovereignty. With its self-hosted model, Zulip ensures that user data remains secure, private, and compliant with organizational data policies, unlike commercial chat platforms.

⭐ 25,587 Stars
šŸ“ 10,012 Forks
ā— 0 Open Issues
šŸ·ļø Apache-2.0
Apache-2.0

Matterbridge is a modular, open-source messaging bridge that connects disparate instant-messaging platforms, enabling secure, decentralized communication across services like Telegram, WhatsApp, and IRC, without relying on centralized providers like Google Chat. By providing a self-hosted, privacy-focused solution, Matterbridge empowers users to regain control over their digital communication and data, making it an attractive alternative for those seeking a more independent and secure messaging experience.

⭐ 7,537 Stars
šŸ“ 725 Forks
ā— 0 Open Issues
šŸ·ļø Apache-2.0
Apache-2.0

Matrix is an open communication protocol and JavaScript library that enables secure, decentralized, and interoperable messaging and collaboration, offering a privacy-friendly alternative to centralized solutions like Google Chat, with features such as end-to-end encryption and transparent data ownership. By utilizing Matrix, developers can build scalable, custom communication solutions that prioritize user autonomy and security, without sacrificing functionality or user experience.

⭐ 2,159 Stars
šŸ“ 700 Forks
ā— 0 Open Issues
šŸ·ļø Apache-2.0

Frequently Asked Questions

What is the best open source alternative to Google Chat?

Based on GitHub community data (including star count and fork activity), Mastodon stands out as one of the most reliable open-source replacements for Google Chat today.

Why should I use an open-source replacement instead of Google Chat?

Switching to an open-source solution ensures complete data sovereignty, protects your software environment from sudden vendor price hikes, and gives you full transparent control over your tech-stack metadata.