Zulip.

Open-source team chat with unique threaded conversation model

Facts

BigBlueButton (self-host)
Virtual classroom and video conferencing; self-hostable
EU · open-source
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CryptPad
End-to-end encrypted collaboration (FR/EU).
FR · open-source
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Nextcloud Deck
Kanban board app for project management within Nextcloud
DE · open-source
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Flock
Team messaging and collaboration platform with EU data centres
NL · commercial
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FluffyChat
Open-source Matrix chat client with focus on simplicity and privacy
DE · open-source
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HedgeDoc
Markdown collaboration; self-host.
DE · open-source
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Huly
Open-source project management and team collaboration platform
PT · open-source
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HumHub
German open-source social intranet and collaboration platform
DE · open-source
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