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Google Calendar vs Proton Calendar: catalog facts
Google Calendar	Proton Calendar
Free Free with a Google account.	Freemium Free account available, with paid Proton plans and a business version.
Web	Android, iOS, Web
Free to use Syncs across devices	End-to-end encryption of event details Built-in scheduling for booking meetings
Requires a Google account Data is stored on Google's servers	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
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 23, 2026

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