Tuta: Free, Cross-Platform and Zero-Knowledge Calendar
Reviewed by Marco Wollank
Tuta
tuta.com 4 ratings so far*
Rate Tuta: No account needed
Threat level
Covered
A covered pick. Anyone can use it as a private drop-in, with no setup or know-how. Enough for most people. Threat levels
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
7,778
+ 110 this week
Last commit
15d ago
healthy
License
GPL-3.0
Latest release
tuta-calendar-android-release-353.260630.0
17d ago
Stars, last 38d
Website at a glance
tuta.com
A+ score 105
Strong website security headers
Graded by Mozilla HTTP Observatory, tested 5d ago
Inspect this site yourself
Measures the security configuration of the tool's own website, not the privacy of the product itself. A strong tool can still score low here.
Tuta alternatives
Proton Calendar Select the "Mail Plus" or "Proton Unlimited" paid plans for more features.
EteSync If you decide to self-host EteSync you won't have to pay for the subscription. Tutorial here .
Radicale A simple self-hosted CalDAV and CardDAV server for calendars and contacts, written in Python and licensed under GPLv3.
Peergos Audited by Cure53 in May 2019.
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.
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