Thunderbird vs OneCalendar: catalog facts
 Thunderbird |  OneCalendar |
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Free Free forever, funded by donations. |
Free Free to download from the app stores. |
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Windows, macOS, Linux, Android |
Windows, macOS, Android, iOS |
- Unified inbox across every account, or each account kept separate, your choice
- Mail, calendar, contacts and tasks in one application rather than four
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- Supports Google, Outlook, Exchange, iCloud, CalDAV and many other providers
- Available on Android, iPhone, iPad, Mac and Windows
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- The interface carries a lot of history and can feel dense next to a webmail tab
- Major ESR releases have historically been disruptive for add-ons and settings
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- Closed source
- No Linux version
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Downloadable app |
Downloadable app |
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Open source |
Closed source |
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License: MPL-2.0 |
License not stated |
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No account needed |
Not stated if an account is needed |
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Works offline |
Works offline |
Checked September 20, 2026 | Checked October 2, 2026 |
Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.
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