Outlook CalDav Synchronizer is a free Outlook Plugin, that can synchronize events, tasks and contacts between Outlook and a CalDAV or CardDAV server*. Amongst others, it supports synchronisation between Google, SOGo, and Horde, and it supports 3Outlook versions 2016, 2013, 2010 and 2007.

Version	3.3.0
Operating System Support	Windows 8, Windows 2012, Windows 2008, Windows Vista, Windows 7, Windows 2003, Windows XP, Windows 2000, Windows 10, Windows 98
Current Language	English
Available Languages	English, French, Polish, Chinese, Italian, German, Japanese, Spanish
License	Free
Date	Tuesday, December 11th 2018
Developer	Alex Nimmervoll
Developer URL	https://www.github.com/aluxnimm

Key Features include:

Two-way-sync.
Modern WPF GUI.
Supporting OAuth2 for Google.
SSL/TLS support, support for self-signed certificates.
Manual proxy configuration support for NTLM or basic auth proxies.
Auto discovery of calendars and address books.
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.
CardDAV support to sync contacts (distribution lists planned).
Google native Contacts API support with mapping of Google contact groups to Outlook categories..
Google Task lists support (sync via Google Task Api with Outlook task folders).
sync contact pictures, categories, notes and x509 certificates.
Time-triggered sync.
Manual-triggered sync.
Change-triggered sync.
Category Filtering (sync CalDAV calendar to Outlook categories).
Map CalDAV server colors to Outlook category colors.
Show reports of last sync runs and status.
Configurable system Tray Icon with notifications.
Bulk creation of multiple profiles.

*Tested CalDAV servers include: SOGo, Google Calendar, Horde Kronolith, OwnCloud, SabreDAV, Synology NAS, GroupOffice, one.com, Yandex, OpenX-change, Posteo, Landmarks, Kolab, Zoho Calendar, GMX, Tine 2.0, Fruux, Mac OS X Server, iCloud, Mail.ru, Radicale.