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Calendars by Readdle vs Calendar 366: catalog facts
Calendars by Readdle	Calendar 366
Free Free to download from the App Store and as a Mac download.	Freemium Subscriptions are sold through the App Store; check the site for current pricing.
macOS, iOS	macOS, iOS
Natural language event creation Calendars and tasks in one view	Events and tasks shown together in one calendar Natural-language event entry
Apple platforms only No Windows or Android 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
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 1, 2026	Official website Full listing and sources Checked October 2, 2026

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