Outlook CalDav Synchronizer is a free Outlook Plugin, which synchronizes events, tasks and contacts between Outlook and Google, SOGo, Horde or any other CalDAV or CardDAV server. Supported Outlook versions are 2016, 2013, 2010 and 2007.

This project was initially started in 2015 as a master thesis project at the University of Applied Sciences Technikum Wien, Software Engineering Degree program and is now powered by Generalize-IT Solutions OG, FN 466962i, 1210 Vienna, Austria.

Outlook CalDav Synchronizer is Free and Open-Source Software (FOSS), still you can support the project by donating here or directly within the About dialog of our Plugin.


Sources and Releases



The only open source CalDAV and CardDAV plugin offers two-way sync for CalDAV calendars and tasks, CardDAV contacts and can also handle the Google native Contacts and Tasks API.

It will handle Outlook categories, mapping CalDAV server colors to Outlook category colors and syncing calendars and tasks to the categories. The plugin also handles timezones and recurring events with exceptions and can deal with Outlook custom properties.

  • open source AGPL, the only free Outlook CalDav plugin
  • two-way-sync
  • SSL/TLS support, support for self-signed certificates and client certificate authentication
  • Manual proxy configuration support for NTLM or basic auth proxies
  • Autodiscovery of calendars and addressbooks
  • configurable sync range
  • sync multiple calendars per profile
  • sync reminders, categories, recurrences with exceptions, importance, transparency
  • sync organizer and attendees and own response status
  • task support
  • Google native Contacts API support with mapping of Google contact groups to Outlook categories.
  • Google Tasklists support (sync via Google Task Api with Outlook task folders)
  • CardDAV support to sync contacts
  • Map Outlook Distribution Lists to contacts groups in SOGo VLIST, KIND:GROUP or iCloud group format
  • time-triggered-sync
  • change-triggered-sync
  • manual-triggered-sync
  • Support for WebDAV Collection Sync (RFC 6578)
  • Category Filtering (sync CalDAV calendar/tasks to Outlook categories)
  • map CalDAV server colors to Outlook category colors
  • show reports of last sync runs and status
  • System TrayIcon with notifications
  • bulk creation of multiple profiles
  • Use server settings from Outlook IMAP/POP3 account profile
  • Map Windows to standard IANA/Olson timezones
  • Configurable mapping of Outlook custom properties
  • create DAV server calendars/addressbooks with MKCOL
  • Map Outlook formatted RTFBody to html description via X-ALT-DESC attribute
  • Support for RFC7986 per-event color handling, mapping of Outlook category color to COLOR attribute

Preconfigured server profiles


Tested servers

– Baïkal – Cozy Cloud – cPanel – Cyrus Imap 2.5 – DAViCal – Fruux – GMX – Google Calendar – Group-Office – Horde Kronolith – iCloud – Kolab – Landmarks – Mac OS X Server – mail.de – mail.ru – mailbox.org – Nextcloud – One.com – OpenX-change – Owncloud – Posteo – Radicale – SabreDAV – SmarterMail – SOGo – Synology DSM – Tine 2.0 – Yahoo – Yandex – Zimbra 8.5 – Zoho Calendar – Web.de

Recommended Client for Android

CalDAV/CardDAV for Android

Used Libraries