Outlook CalDav Synchronizer
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 2021, 2019, 2016, 2013, 2010 and 2007 and Office 365 for Desktop.
Project Homepage
http://caldavsynchronizer.org
License
Affero GNU Public License
Authors
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 on Sourceforge or directly at PayPal
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Collaboration with Nextcloud
For our collaboration with Nextcloud, see https://nextcloud.com/blog/nextcloud-offers-caldav-synchronizer-for-outlook-users/
For possible enterprise support, please contact us here!
Recommended Android DAV client
We work closely together and test interopability with DAVx⁵ for Android,
see https://www.davx5.com, so we can really recommend it! Together with DAVx⁵ we now have experimental support for per-event coloring by mapping the Outlook category color to the COLOR attribute of the event.
Tested CalDAV Servers
- Baïkal
- Cozy Cloud
- cPanel
- Cyrus Imap 2.5
- DAViCal
- EGroupware
- FastMail
- Fruux
- GMX
- Google Calendar
- Group-Office
- Horde Kronolith
- iCloud
- Kolab
- Landmarks
- Mac OS X Server
- mail.ru
- mailbox.org
- Nextcloud
- One.com
- Open-Xchange
- Owncloud
- Posteo
- Radicale
- SabreDAV
- SmarterMail
- SOGo
- Synology DSM
- Tine 2.0
- Yahoo
- Yandex
- Zimbra 8.5
- Zoho Calendar
Features
- open source AGPL, the only free Outlook CalDav plugin
- two-way-sync
- Localization support
- 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
Used Libraries
Install instructions
WARNING: Beginning with release 4.0.0 .NET framework 4.8 is the minimal requirement.
Download and extract the OutlookCalDavSynchronizer-.zip into any directory and start setup.exe. You can change the default install path, but you need to use a directory on the C:\ drive.
If the installer is complaining about the missing Visual Studio 2010 Tools for Office Runtime, install it manually from Microsoft Download Link
You should also update manually to the latest Visual Studio 2010 Tools for Office Runtime (Version 10.0.60912) if you have an older version installed, since some COMExceptions have been fixed.
Beginning with version 2.9.0 the default install location is ProgramFilesDir\CalDavSynchronizer\ and the installer remembers the chosen directory for the next updates. Also the install option to install for Everyone instead of the current user is working now for Outlook 2010 and higher, if you want to install the addin for all users on the current machine. For Outlook 2007 you can only install the addin for the current user.
We recommend updating to the latest .Net Framework but the minimal required version is .NET 4.8, which is not supported on Windows XP, Windows 8 or Windows Vista. If you need Outlook CalDav Synchronizer for Windows XP you can download a backport to .Net 4.0 from a forked project here, thanks to Salvatore Isaja for the awesome work!
Changelog
4.7.1
- Released 2026/08/17
- Bug fixes
- Fix gh issue 478,479, SourceForge #2181,#2179 empty address strings in Attendee Mapping.
4.7.0
- Released 2026/08/10
- Security fix
- harden XML parsing logic to avoid XML External Entity (XXE) injection.
- New features
- Upsate NuGet packages.
- Add Postassl profile.
- Bug fixes
- Properly quote display name when using e-mail address syntax
to specify an attendee or organizer to Outlook.
4.6.0
- Released 2025/06/04
- New features
- Update NuGet packages.
- Add Aruba profile.
4.5.0
- Released 2024/12/26
- New features
- Update NuGet packages.
- Use Unicolour library for colour comparison and remove ColorMine package.
- Use json site to query newest version.
4.4.1
- Released 2023/04/06
- Bug fixes
- fix regression bug gh 388, recurring events and tasks with COUNT!=0, sourceforge #1770.
4.4.0
- Released 2023/03/21
- New features
- Implement PKCE for Swisscom Oauth2 requests.
- Update NuGet packages.
- Update mailbox.org logo.
- Optimize vCardStandardReader/Writer and use LINQ.
- Implement a new RemoveInvalidXmlCharacterStreamReader for option Accept invalid chars in server response.
- Bug fixes
- Fix typo and add translation for Close profile window dialog.
- ignore empty photo URI, sourceforge ticket #1822.
- Enable force basic authentication as default for new profiles, with CredentialCache there are issues with accentuated characters in passwords, issue #1774, gh issue 363.
- Don't serialize password and salt for profiles where UseAccountPassword is enabled, gh issue 364.
- Don't serialize ProxyPassword when DefaultProxy is enabled.
- Catch possible exceptions in accessing MAPI folder when getting ItemCount, should fix profile load if folders are not accessible, gh issue 310,381.
- Explicitely set NoEndDate to true for recurring events and tasks, gh issue 334.
- Remove invalid xml chars from appointment, task and vcard encoded strings.
4.3.0
- Released 2022/07/05
- Security Fixes
- Update NuGet packages. (fixes security vulnerability in Newtonsoft.Json).
- New features
- Add Simplified Chinese (中国) [zh-CN] translation. Credits to Liu Yihua (yihuajack)
- Add untermStrich profile type.
- Bug fixes
- Hide PasswordBox when UsaAccountPassword is enabled to improve profile creation ServerSettings dialog.
- Fix typos in fr-FR translation.
- Fix WebDavSync setting in profile selection after folder change.
4.2.0
- Released 2022/03/02
- Security fixes
- Update NuGet package for log4net, CVE-2018-1285, gh issue 343.
- Bug fixes
- fix handling close of OptionsWindow.
- reset all telephone numbers not only main ones, gh issue 342.
- Validate Swisscom profile and check if contact folder is selected.
- Default to CardDAV for Google bulk profile since native API changed and needs to be updated.
- Fix autodiscovery and ignore 400 error when querying Google CardDAV adress book resource.
- Known Issues
- Google Contact API changed and therefore is not supported anymore, please use CardDAV instead of Google native API meanwhile.
4.1.0
- Released 2021/05/12
- New features
- New Addressbook Profile handling for Profile Type Swisscom.
- Use Google oauth library for authentication in Swisscom profile.
- Update Google NuGet libraries.
- Bug fixes
- Set CurrentUICulture in CompontentContainer startup to avoid issues where Localization didn't work in some dialogs, e.g. github issue 241.
- Improve naive string handling in vcard parser library, fixed performance issues when syncing large pictures, github isse 299.
4.0.0
- Released 2020/11/30
- WARNING: This release is a major upgrade and needs .NET framework 4.8 as minimal requirement. Automatic upgrade won't work if you still have only .NET framework 4.6.1 installed. Install and upgrade manually in that case!
- New features
- Support for .NET framework 4.8
- Support for TLS 1.3
- Update Google Task API
- Update NuGet libraries
- Add Fuago contact for Ooutlook Sync for OX, contact [email protected].
- Bug fixes
- Fix sync for empty task lists and check also for hidden tasks (needed for completed tasks), fixes ticket #1377 and gh issue 280
- Fix PostBuildEvent to sign also setup.exe
- Remove Microsoft.Bcl.Build reference
- Migrate to package references and VS 2019
3.8.2
- Released 2020/06/30
- Bug fixes
- Fix "install new version" button width for non english locales.
- Fix assembly info version for OAuth.Swisscom project and link to CalDavSynchronizer files.
3.8.1
- Released 2020/06/24
- Bug fixes
- HOTFIX: Suppress javascript errors during swisscom oauth.
3.8.0
- Released 2020/04/09
- New features
- Support also external members with email and CN in iCloud groups for DistributionList mapping.
- Bug fixes
- Update Google API and other NuGet packages.
- Use Utc for aVersion LastModification timestamps in cache to avoid full resync when Windows timezone changes, ticket #1266.
- Update code signing certificate.
3.7.0
- Released 2019/11/14
- New features
- Add support for resources with urn:uuid values and EMAIL property in attendees.
- Add principal-property-search report to find resource id from displayname.
- Add support for X-KIND and X-MEMBER in vCard for contact groups, ticket #1267.
- Bug fixes
- Fix mapping of completed tasks if PercentComplete is not set. Tickets #1211 and #1273.
- Fix import profile windows title, ticket #1235.
3.6.2
- Released 2019/06/26
- Bug fixes
- Manually set authorization header if forceBasicAuthentication is checked to fix issues with some server configs which fail with 401 otherwise.
- Update WebResourcUrls