Open-source alternatives to Microsoft Teams

Here is a list of open-source alternatives to Microsoft Teams, from Open Source Everything (CC BY-SA 4.0): - Rocket.Chat (MIT, https://github.com/RocketChat/Rocket.Chat; replaces fully): Rocket.Chat is a team messaging platform for real-time chat, voice calls and federation between organizations. It is aimed at workplaces and organizations that want to host their own chat with strong data protection. - Mattermost (AGPL-3.0, https://github.com/mattermost/mattermost; replaces fully): Mattermost is a team chat platform that you install on your own server, so your company's messages stay under its control. It is aimed at workplaces and IT teams that want chat, workflow automation and voice calls in one place. - Zulip (Apache-2.0, https://github.com/zulip/zulip; replaces fully): Zulip is a team chat app where conversations are organized by topic, so it combines features of email and chat. It is for workplaces and open-source projects, and can be used on the web or self-hosted on your own server. - Element (AGPL-3.0, https://github.com/element-hq/element-web; replaces fully): Element is a chat app for private messages and group chats over the Matrix network, used in a web browser or as a desktop app. It is for people and teams who want chat they can host and control, with phone apps offered as separate Element X projects. - Jitsi Meet (Apache-2.0, https://github.com/jitsi/jitsi-meet; replaces fully): Jitsi Meet is a free video meeting tool that runs in a web browser or a mobile app, with screen sharing, chat and polls. It can be used on the public meet.jit.si site or installed on your own server. - BigBlueButton (LGPL-3.0, https://github.com/bigbluebutton/bigbluebutton; replaces partly): BigBlueButton is a free video classroom where teachers and students meet online, share audio, video, slides, screens and chat. It is aimed mainly at schools, tutors and online courses, and you install it on your own server. - Nextcloud Talk (AGPL-3.0, https://github.com/nextcloud/spreed; replaces partly): Nextcloud Talk is a video and audio calling app with text chat, screen sharing and password-protected calls. It is for people and teams who run their own Nextcloud server and want calls on it instead of a commercial service. - Galene (MIT, https://github.com/jech/galene; replaces partly): Galene is a videoconferencing server you run yourself so groups can hold video calls in a web browser. It is aimed at people or organizations who want to host their own meetings and need it to use few server resources. - Element Call (AGPL-3.0, https://github.com/element-hq/element-call; replaces partly): Element Call is a video and voice calling app built on the Matrix protocol, so calls can work across different servers. It is for people and organizations who want encrypted video meetings without relying on a single company's servers. - Jami (GPL-3.0, https://github.com/savoirfairelinux/jami-client-qt; replaces partly): Jami is a free app for video calls, chat and file sharing. It works without a central company server, so it suits people who want private communication. Compare it with my project or idea below. Tell me which projects overlap, what I could reuse instead of rewriting, and what mine does that none of them do. My project or idea: