K-9 Mail vs Thunderbird: catalog facts
 K-9 Mail |  Thunderbird |
|---|
|
Free Free and open source. |
Free Free forever, funded by donations. |
|
Android |
Windows, macOS, Linux, Android |
- Open source with a long track record on Android
- Now the foundation for Thunderbird's official mobile app
|
- Unified inbox across every account, or each account kept separate, your choice
- Mail, calendar, contacts and tasks in one application rather than four
|
- Android only, no iOS version
- Interface is more utilitarian than modern polished mail apps
|
- 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
|
|
Downloadable app |
Downloadable app |
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Open source |
Open source |
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License: Apache-2.0 |
License: MPL-2.0 |
|
Not stated if an account is needed |
No account needed |
|
Not stated if it works offline |
Works offline |
Checked September 22, 2026 | Checked September 20, 2026 |
Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.
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