Outlook CalDav Synchronizer is a free Outlook Plugin, which synchronizes events, tasks and contacts between Outlook and Google, SOGo, Nextcloud or any other CalDAV or CardDAV server. Supported Outlook versions are Office 365, 2019, 2016, 2013, 2010 and 2007.
Publisher’s description
What is CalDavSynchronizer?
CalDavSynchronizer is an open-source cloud storage & sync program for Windows from Gerhard Zehetbauer. It ranks 16th by popularity among cloud storage & sync in this catalogue. It is written in C#.
Installation and requirements
Official installers exist for 64-bit and 32-bit as MSI. The installer supports unattended (silent) installation.
Updates and version history
The current version is 4.7.1, released on August 17, 2026. 5 versions are listed since March 21, 2023, each with links to its own installer files. That is about 1.5 releases a year.
Popularity and file types
The Chocolatey package has been downloaded 92,497 times. The source code on GitHub (aluxnimm/outlookcaldavsynchronizer) has 1,095 stars. Similar programs include Syncthing, AWS Command Line Interface and Dropbox.
Project description on GitHub: “Sync Outlook with Google, SOGo, Nextcloud or any other CalDAV/CardDAV server”
Pros / Cons
Pros
- Open source: the code can be inspected and built by anyone
- Documented silent install
Cons
- No native ARM64 build
In short: CalDavSynchronizer is an open-source cloud storage & sync tool for 64-bit and 32-bit PCs. Administrators can deploy it unattended.
Is CalDavSynchronizer safe to download?
- The file is served by github.com, the publisher’s own domain
- The download link uses HTTPS
- A SHA256 hash is published, so you can verify the file:
46AE790A0518936AD1E58D3C6723F53497136D35E88B1AF56C1DFE299686846C· Open the VirusTotal report for this hash - The link has not been checked yet
- The source code is public
- ExeAtlas does not host, wrap or modify installers
Related guide: How to check a file’s SHA256 hash on Windows
Security practices (OpenSSF Scorecard)
Automated checks of the aluxnimm/outlookcaldavsynchronizer repository on GitHub by the Open Source Security Foundation, last run on October 19, 2026.
- Actively maintained10
- Licence declared10
- No binaries in the repository9
- Code review0
- OpenSSF Best Practices badge0
- Security policy0
- Fuzzing0
- Signed releases0
- Branch protection0
- Static code analysis0
The score rates how the project is developed and released, not whether the program is safe to install. scorecard.dev
Recent versions
All 5 versions ›5 versions over 3 years · about 1.5 a year
| Version | Date | Size | Files |
|---|---|---|---|
| 4.7.1Latest | August 17, 2026 | — | 32-bit ZIP64-bit ZIP |
| 4.7.0 | August 10, 2026 | — | 32-bit ZIP64-bit ZIP |
| 4.6.0 | June 4, 2025 | — | 64-bit ZIP32-bit ZIP |
| 4.5.0 | December 26, 2024 | — | 32-bit ZIP |
| 4.4.0 | March 21, 2023 | — | 32-bit ZIP |
Install from the command line
Silent install ›winget install --id aluxnimm.OutlookCalDavSynchronizer -echoco install Outlookcaldav -ymsiexec /i OutlookCalDavSynchronizer-4.7.1.zip /qn /norestartmsiexec /x {ED085E9E-07AC-4D26-9ED5-25B5C813DB91} /qn /norestartRelated guide: How to use winget: install and update apps
Information
- Publisher
- Gerhard Zehetbauer
- Category
- Cloud storage & sync
- Licence
- AGPL-3.0
- Price
- Free
- Source code
- github.com/aluxnimm/outlookcaldavsynchronizer
- Written in
- C#
- Requires
- Windows 11 / 10
- Architecture
- 64-bit, 32-bit
- Installer
- MSI
- Version
- 4.7.1
- Released
- August 17, 2026
- Added to the catalogue
- July 27, 2025
- Versions listed
- 5
- Updates / year
- 1.5
- Chocolatey downloads
- 92,497
- GitHub stars
- 1,095
- GitHub forks
- 109
- Website
- caldavsynchronizer.org
- winget ID
- aluxnimm.OutlookCalDavSynchronizer
- Chocolatey package
- Outlookcaldav
- MSI product code
- {ED085E9E-07AC-4D26-9ED5-25B5C813DB91}
Ratings and reviews
No reviews yet. Be the first to rate it.
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Frequently asked questions
Is CalDavSynchronizer free?
Yes. CalDavSynchronizer is open-source software under the AGPL-3.0 licence.
Is CalDavSynchronizer safe to download?
The download comes from github.com, which belongs to the publisher; ExeAtlas does not host or change the file. Compare its SHA256 hash with the one shown here, or open the VirusTotal report for that hash.
How do I install CalDavSynchronizer with winget?
Open PowerShell or Windows Terminal and run the winget command shown on this page. winget downloads the official installer and checks its SHA256 hash before running it.
Can CalDavSynchronizer be installed silently?
Yes. The silent install page lists the exact command for each installer.
Does CalDavSynchronizer run on ARM (Windows on Arm)?
There is no ARM64 build; Windows 11 on Arm can run the 64-bit and 32-bit version through emulation.
Where can I download an older version of CalDavSynchronizer?
The versions page lists all 5 versions with links to their official installer files, back to March 21, 2023.
What are alternatives to CalDavSynchronizer?
Syncthing, AWS Command Line Interface, Dropbox, Rclone and heroku. The alternatives page compares them.
