Calendar privacy ratings
Calendar apps and services.
12 calendars are rated against 4 public criteria, and 12 have enough evidence for a letter grade. Of the 7 with a known jurisdiction, 3 are based in a Five Eyes country, and 5 in the wider Fourteen Eyes.
Open-source calendars only · Criteria for this category · Suggest an addition · Markdown
| Name | Grade | Score | Data | Jurisdiction | Open source | No trackers or telemetry | No ads or data sales | Independent audit |
|---|---|---|---|---|---|---|---|---|
CalDAV calendar, task and CardDAV contacts service included with paid Forward Email plans. It works with any CalDAV or CardDAV app and with Forward Email's own webmail, desktop and mobile apps, and stores data in each alias's encrypted SQLite mailbox. |
Grade B | 85 | 100% | United States Five Eyes | Yes | Partial | Yes | Yes |
Self-hosted CalDAV and CardDAV server written in PHP and built on the sabre/dav library, with a web interface for managing users, calendars and address books. |
Grade B | 80 | 100% | – | Yes | Yes | Yes | No |
Android app that syncs calendars, contacts, tasks and files with CalDAV, CardDAV and WebDAV servers, so they appear in the device's own calendar and contacts apps. |
Grade B | 80 | 100% | Austria Outside Eyes | Yes | Yes | Yes | No |
Open source Android calendar app based on the AOSP Calendar. Shows calendars stored on the device, including offline calendars and CalDAV calendars synced by an app such as DAVx5. |
Grade B | 80 | 100% | – | Yes | Yes | Yes | No |
Offline Android calendar from Fossify, a community fork of Simple Mobile Tools. Supports widgets, reminders and ICS import and export, and can show CalDAV calendars synced by an app such as DAVx5. |
Grade B | 80 | 100% | – | Yes | Yes | Yes | No |
Offline-first Android calendar that syncs with iCloud, CalDAV and the device calendar. Needs no account, has no telemetry and stores credentials in the Android Keystore. |
Grade B | 80 | 100% | – | Yes | Yes | Yes | No |
Calendar app for self-hosted Nextcloud servers. Syncs across devices with CalDAV and supports shared calendars and appointment booking. No end-to-end encryption. |
Grade B | 80 | 100% | Germany Fourteen Eyes | Yes | Yes | Yes | No |
Lightweight self-hosted CalDAV and CardDAV server written in Python, for syncing calendars, contacts and task lists across devices. Stores data as plain files. |
Grade B | 80 | 100% | – | Yes | Yes | Yes | No |
End-to-end encrypted calendar from Tuta, available as a standalone Android and iOS app and in Tuta's web and desktop clients. Events, invitations and shared calendars are encrypted. |
Grade C | 65 | 100% | Germany Fourteen Eyes | Partial | Yes | Yes | No |
End-to-end encrypted calendar from Proton for web, Android and iOS. Supports shared calendars, recurring events, time zones, ICS import and subscriptions, and integrates with Proton Mail. |
Grade C | 60 | 100% | Switzerland Outside Eyes | Partial | Partial | Yes | Partial |
Google's calendar service for web, Android and iOS, with shared calendars, event invitations and integration with Gmail and Google Meet. |
Grade F | 10 | 100% | United States Five Eyes | No | No | No | Partial |
Microsoft's calendar built into Outlook on the web, Windows, macOS, Android and iOS, used with Outlook.com and Microsoft 365 accounts. Supports shared calendars, meeting scheduling and Teams integration. |
Grade F | 10 | 100% | United States Five Eyes | No | No | No | Partial |
Questions
What is the most private option among calendars?
No pick has been made yet. The table above is sorted by score, based on public evidence.
How are calendars rated?
Each entry answers 4 questions: open source, no trackers or telemetry, no ads or data sales and independent audit. Answers need links to evidence. See the full criteria.
Does jurisdiction matter?
Jurisdiction decides which laws can compel a provider to hand over data. Each entry shows its country and whether it is in the Five, Nine or Fourteen Eyes. The data a provider can hand over depends mostly on what it stores and who holds the keys. Read about jurisdictions and the CLOUD Act.