Tuta: Free, Cross-Platform and Zero-Knowledge Calendar
Official website tutanota.com/calendar
Our take
A zero-knowledge, cross-platform calendar with a real free tier, tightly bound to its encrypted mail, which is both the appeal and the constraint. Encryption means it doesn’t speak standard CalDAV, so syncing with outside apps is limited and you’re committing to the Tuta app to use it well. That lock-in is the price of the privacy. A strong choice if you’re already in or moving to its email; awkward if you want a calendar that plugs into everything else.
GitHub at a glance
tutao/tutanota
Stars
7,694
+ 26 this week
Last commit
today
healthy
License
GPL-3.0
Latest release
tutanota-release-351.260612.0
4d ago
Stars, last 9d
Listed in
Tuta alternatives
Tuta license, in plain English
GPL-3.0 Strong copyleft
Free to use and modify, but anything you distribute that is built on it must also be open under the same license.
Permits
- Commercial use
- Modification
- Distribution
- Patent use
- Private use
Requires
- Disclose source
- Same license
- State changes
- License and copyright notice
Does not provide
- Liability cover
- Warranty
Why it matters: Strong copyleft keeps every distributed version open. A vendor cannot fold this into a closed product and ship it without releasing their changes.
Plain-language summary of the project's license, not legal advice. Read the full text for the exact terms.