'Matrix' Network Hits 60 Million Users, Improving the Demand for Decentralized Communication
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Matrix is an open-source standard for decentralized communication. It is constantly evolving to the requirements of modern solutions keeping in mind the privacy of users. You will find Matrix clients as a replacement for Slack, Microsoft Teams, and several other popular communication platforms. And, to re-affirm the adoption of decentralized

Not sure why Signal gets all the attention when Matrix is much more successful at spreading open source messaging and is also decentralized.