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Kolab Now vs Proton Calendar: catalog facts
Kolab Now	Proton Calendar
Paid Paid subscription service.	Freemium Free account available, with paid Proton plans and a business version.
Web	Android, iOS, Web
Operated in Switzerland since 2013 Email, calendars, contacts, files and video calls in one account	End-to-end encryption of event details Built-in scheduling for booking meetings
Hosted service, not something you run yourself Paid service	Requires a Proton account Works best within the Proton ecosystem
Web application, Hosted service	Downloadable app, Web application, Hosted service
Closed source	Closed source
License not stated	License not stated
Account needed	Account needed
Needs internet	Not stated if it works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.