How sync works
Every sync works on the same principle: busy times flow from one or more source calendars into a target calendar. There, Kalender Sync creates its own blocker events — and manages exclusively those.
Always one direction
Section titled “Always one direction”- Every sync transfers from source → target. If two calendars should block each other, set it up in both directions.
- Your original events are never modified — no matter what. Kalender Sync only touches its own blockers.
- Event moved in the source? The blocker moves along. Deleted? The blocker disappears.
How fast is sync?
Section titled “How fast is sync?”| Source | Mechanism | Speed |
|---|---|---|
| Google, Microsoft | Provider pushes changes (webhooks, all plans) | almost instant — typically under a minute |
| Apple iCloud, GMX, WEB.DE, mailbox.org, Posteo, STRATO, Disroot, KSuite, iCal feeds | Regular polling | every 5 minutes |
Real-time webhook sync for Google and Microsoft is active on every plan, including Free. Apple iCloud, GMX, WEB.DE, mailbox.org, Posteo, STRATO, Disroot, KSuite and iCal feeds (Basic and up) are polled every 5 minutes (Plans & limits).
On top of that there’s a safety net: every few hours Kalender Sync fully reconciles each sync, catching changes that slipped through (e.g. a lost provider notification). So if an event seems missing — it often resolves itself on the next reconciliation. If not: Event missing, duplicated or late.
The initial sync after setup processes the backlog and can take a few minutes (up to half an hour for large calendars) — you’ll receive an email once it’s done.
What gets synced — and what doesn’t
Section titled “What gets synced — and what doesn’t”- Events within the sync window: 3 months into the past; into the future depending on your plan: 6 months (Free & Basic) or 18 months (Professional).
- How much content arrives is controlled by the visibility level — from “busy only” to full details.
- Never transferred: attendee lists, email addresses, organisers, accept/decline responses. All-day events are treated as free by default.
Protection against loops and duplicates
Section titled “Protection against loops and duplicates”Kalender Sync marks every blocker it creates and never syncs it onward — no ping-pong between linked calendars and no duplicates, not even in chained setups across three or more calendars.
On pausing and ending
Section titled “On pausing and ending”- Paused: sync stops, existing blockers stay. On resume, the state is reconciled.
- Ended: all blockers created by Kalender Sync in the target are cleaned up automatically. Details: Pause or end a sync.