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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.

Kalender Sync dashboard with connected calendars and active syncs
The dashboard: connected calendars on top, the active syncs below.
  • 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.
SourceMechanismSpeed
Google, MicrosoftProvider pushes changes (webhooks)almost instant — typically under a minute
Apple iCloud, KSuite, iCal feedsRegular pollingevery 5 minutes

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.

  • Events within the sync window of 3 months back to 6 months ahead.
  • 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.

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.

  • 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.