Compare software

Microsoft OutlookBetterbird
Freemium

Free app and account available; Microsoft 365 plans add paid features and Office apps.

 Free

Free and open source, funded by donations.

Windows, macOS, Android, iOS, Web Windows, macOS, Linux
  • Email, calendar and contacts for multiple accounts in one app
  • Available on desktop, mobile and 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
  • Closed source and tied to Microsoft services
  • Some features, including Copilot, require a paid plan
  • 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
Downloadable app, Web application Downloadable app
Closed source Open source
License not stated License: MPL-2.0
Not stated if an account is needed No account needed
Not stated if it works offline Works offline

Checked September 23, 2026

Checked September 20, 2026

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