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Notion Calendar vs Etar: catalog facts
Notion Calendar	Etar
Free Free to use.	Free Free and open source.
Windows, macOS, Android, iOS	Android
Free Tight integration with Notion databases and docs	Open source with an active community Clean Material Design interface
Built around Google Calendar and Notion Proprietary	Android only Sync depends on the calendar accounts set up on the phone
Downloadable app	Downloadable app
Closed source	Open source
License not stated	License: GPL-3.0
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 September 23, 2026	Official website Full listing and sources Checked September 24, 2026

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