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Microsoft Outlook for iOS and Android vs Fossify Calendar: catalog facts
Microsoft Outlook for iOS and Android	Fossify Calendar
Freemium The app is a free download; Microsoft 365 plans are sold separately.	Free Free and open source with no ads.
Android, iOS	Android
Email, calendar and contacts in one app Available on both iOS and Android phones and tablets	No ads or tracking Syncs with Google, Outlook, Nextcloud and Exchange calendars
Closed source Closely tied to Microsoft's services and plans	Android only Sync relies on accounts already set up on the device
Downloadable app	Downloadable app
Closed source	Open source
License not stated	License: GPL-3.0-only
Not stated if an account is needed	No account needed
Not stated if it works offline	Works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked October 2, 2026

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