Finally in Sync.
Everywhere.

When you add accounts to Outlook, only you see the combined view. Other people checking your availability through Outlook's scheduling assistant only see free/busy from one tenant. twiin syncs your calendars so that your unified availability is visible to everyone scheduling with you—not just yourself.

No. Sync decisions are based solely on calendar item IDs. Only these IDs are transmitted to coordinate the sync—they contain no personal information and allow no conclusions about your calendar content. Your actual event data never leaves your device.

No. twiin works with standard user permissions. You only need the ability to sign in to each account. No IT department involvement required.

twiin needs to be running to keep your calendars in sync. If you go offline, no worries—the moment you're back online, twiin picks up right where it left off and syncs everything automatically.

Yes. You have full control over each sync flow—choose which calendars participate, set one-way or bidirectional sync, and decide exactly what gets synced: full event details, just free/busy blocks, or event names only.

twiin is available for macOS (11 Big Sur and later) and Windows (10 and later).

Your calendar data remains safely in your original Microsoft 365 accounts. twiin only syncs between them—it doesn't become a single point of failure. Uninstall anytime without data loss.