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Calendars by Readdle vs Microsoft Outlook: catalog facts
Calendars by Readdle	Microsoft Outlook
Free Free to download from the App Store and as a Mac download.	Freemium Free app and account available; Microsoft 365 plans add paid features and Office apps.
macOS, iOS	Windows, macOS, Android, iOS, Web
Natural language event creation Calendars and tasks in one view	Email, calendar and contacts for multiple accounts in one app Available on desktop, mobile and web
Apple platforms only No Windows or Android version	Closed source and tied to Microsoft services Some features, including Copilot, require a paid plan
Downloadable app	Downloadable app, Web application
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 September 23, 2026

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