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OneCalendar vs Calendar 366: catalog facts
OneCalendar	Calendar 366
Free Free to download from the app stores.	Freemium Subscriptions are sold through the App Store; check the site for current pricing.
Windows, macOS, Android, iOS	macOS, iOS
Supports Google, Outlook, Exchange, iCloud, CalDAV and many other providers Available on Android, iPhone, iPad, Mac and Windows	Events and tasks shown together in one calendar Natural-language event entry
Closed source No Linux version	Apple platforms only Pricing details are not stated on the homepage
Downloadable app	Downloadable app
Closed source	Closed source
License not stated	License not stated
Not stated if an account is needed	Not stated if an account is needed
Works offline	Not stated if it works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked October 2, 2026

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