Google Workspace.

Google's cloud-based collaboration and productivity tools

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Open-Xchange
European open-source email, calendar, and productivity suite
DE · 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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ONLYOFFICE
European office collaboration suite with self-hosting option
LV · open-source
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mailbox.org
German email and groupware.
DE · commercial
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Kopano
Dutch groupware with self-host options
NL · open-source
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Proton
Swiss encrypted email, calendar, drive and VPN suite
CH · commercial
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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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