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Betterbird vs Microsoft Outlook: catalog facts
Betterbird	Microsoft Outlook
Free Free and open source, funded by donations.	Freemium Free app and account available; Microsoft 365 plans add paid features and Office apps.
Windows, macOS, Linux	Windows, macOS, Android, iOS, Web
Fixes and features Thunderbird has not shipped, listed openly in a comparison table Installs next to Thunderbird and runs on the same profile, so switching back is trivial	Email, calendar and contacts for multiple accounts in one app Available on desktop, mobile and web
A small volunteer project riding on someone else’s release train The Mac build ships in English only and needs a language pack for anything else	Closed source and tied to Microsoft services Some features, including Copilot, require a paid plan
Downloadable app	Downloadable app, Web application
Open source	Closed source
License: MPL-2.0	License not stated
No account needed	Not stated if an account is needed
Works offline	Not stated if it works offline
Official website Full listing and sources Checked September 20, 2026	Official website Full listing and sources Checked September 23, 2026

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