Matrix / Synapse.

Matrix homeserver; self-hostable.

Feiten

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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FluffyChat
Open-source Matrix-chatclient met focus op eenvoud en privacy
DE · open-source
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HedgeDoc
Markdown collaboration; self-host.
DE · open-source
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Huly
Open-source projectmanagement en team-samenwerkingsplatform
PT · open-source
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HumHub
Duits open-source sociaal intranet en samenwerkingsplatform
DE · open-source
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Kopano
Dutch groupware with self-host options
NL · open-source
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Nextcloud
Open-source self-hosted collaboration platform for file sync, chat, and office
DE · open-source
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