# Private and open-source alternatives to Outlook Calendar

1. [Forward Email Calendar](https://privacyratings.com/calendars/forward-email-calendar/): B (85/100). 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.
2. [Baïkal](https://privacyratings.com/calendars/baikal/): B (80/100). 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.
3. [DAVx⁵](https://privacyratings.com/calendars/davx5/): B (80/100). 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.
4. [Etar](https://privacyratings.com/calendars/etar/): B (80/100). 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.
5. [Fossify Calendar](https://privacyratings.com/calendars/fossify-calendar/): B (80/100). 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.
6. [KashCal](https://privacyratings.com/calendars/kashcal/): B (80/100). 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.
7. [Nextcloud Calendar](https://privacyratings.com/calendars/nextcloud-calendar/): B (80/100). Calendar app for self-hosted Nextcloud servers. Syncs across devices with CalDAV and supports shared calendars and appointment booking. No end-to-end encryption.
8. [Radicale](https://privacyratings.com/calendars/radicale/): B (80/100). Lightweight self-hosted CalDAV and CardDAV server written in Python, for syncing calendars, contacts and task lists across devices. Stores data as plain files.
9. [Tuta Calendar](https://privacyratings.com/calendars/tuta-calendar/): C (65/100). 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.
10. [Proton Calendar](https://privacyratings.com/calendars/proton-calendar/): C (60/100). 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.

Source: https://privacyratings.com/alternatives/outlook-calendar/