How sync works

CalDAVconnect is built to sync within seconds, not the hours you get from ICS feed subscriptions. Here's what happens behind the scenes.

Change detection

CalDAVconnect uses two mechanisms together:

• Push notifications (webhooks) from Google Calendar and Microsoft 365. When something changes in the cloud, the provider notifies us immediately.
• Fast polling of your CalDAV server. CalDAV has no universal push standard, so CalDAVconnect checks efficiently for changes using sync tokens and collection tags (CTags) where the server supports them, and falls back to lightweight periodic checks where it doesn't.

When a change is detected on one side, it is normalized and written to the other side right away.

Sync frequency by plan

• Free — calendars sync about once per hour.
• Solo and Pro — near real-time syncing (typically within seconds), driven by push notifications and fast polling.

Paid plans (Solo and Pro) sync within seconds. The free plan uses an hourly sync interval.

Keeping state consistent

For every synced event, CalDAVconnect stores the last known state (a shadow). This lets it detect what genuinely changed, avoid sync loops, and resolve conflicts sensibly instead of overwriting blindly. A daily full reconciliation also corrects any drift that incremental syncing might miss.

Limits worth knowing

• Recurring events on limited servers. A few CalDAV servers don't fully support recurrence rules (RRULE). CalDAVconnect automatically probes for support and, on incompatible servers, skips recurring events rather than corrupting them. Single events still sync normally.
• Calendar creation. Some providers (e.g. Posteo, mailbox.org) expose only their existing calendar and don't allow creating new calendars from a client. You sync into the existing calendar instead.
• Initial sync window. The first sync focuses on current and upcoming events; very old historical events may not all be imported.

Next

If something isn't syncing as expected, see Troubleshooting & FAQ.