caldavsynchronizer.org

What It Is

Outlook CalDav Synchronizer is a free and open-source Outlook add-in from Generalize-IT Solutions OG. Its purpose is to sync events, tasks, and contacts between Outlook and Google, SOGo, Nextcloud, or other CalDAV/CardDAV servers. It supports Office 365 as well as Outlook 2019, 2016, 2013, 2010, and 2007. Its positioning is very clear: it fills the interoperability gap between Outlook and open calendar/contact protocols.

Core Capabilities

In terms of functionality, it supports two-way synchronization for CalDAV calendars and tasks, CardDAV contacts, and also Google’s native Contacts API and Tasks API. The synchronization coverage is fairly deep, including reminders, categories, recurring events and exceptions, importance, transparency, organizers and attendees, your own response status, Outlook custom properties, time zone mapping, and mapping CalDAV server colors to Outlook category colors. It also supports WebDAV Collection Sync, autodiscovery, multi-calendar synchronization, sync by time/change/manual trigger, system tray notifications, and recent sync reports.

Open Source, Self-Hosting, and Integrations

The project is explicitly FOSS and licensed under the Affero GNU Public License, with source code and releases available on GitHub and SourceForge. It is quite self-hosting friendly: the main documentation clearly states support for any CalDAV/CardDAV server and lists common self-hosted platforms such as Nextcloud and SOGo. It also supports SSL/TLS, self-signed certificates, client certificate authentication, and NTLM or Basic Auth proxy configuration, making it suitable for corporate intranets or private deployment environments. On the ecosystem side, the website recommends DAVx⁵ for Android and mentions partners or integrations such as Nextcloud, DAVx⁵, and easyproject.

Pricing and Documentation

Pricing is very straightforward: it is free and open source, with a donation option on the website. No commercial edition, subscription plan, or enterprise support pricing was found. As for documentation, the feature pages are detailed, and there are also blog posts, video tutorials, source code, and release links. However, the FAQ pages we crawled were mostly marked Under Construction or contained test text, making them obvious placeholders. This suggests that the FAQ documentation is not yet complete.

Pros, Cons, and Who It’s For

Its strengths are that it is free, open source, standards-based, and solid in synchronization detail. It is especially suitable for individuals and organizations that use Outlook while relying on Nextcloud, SOGo, Google, or other DAV services on the backend. The downside is that the product is focused on being a Windows Outlook add-in, with no clear information found for macOS, mobile clients, or Outlook on the web. Commercial support and SLA information are also unclear. The source content did not provide information about accessibility from China, so this cannot be assessed; if GitHub, Google, or related services are involved, the actual experience may be affected by the local network environment.