Two-way sync between Google Calendar and Apple Calendar — not just a read-only mirror
Most “calendar sync” tools only copy events in one direction, or need you to manually export and re-import. Seam keeps both calendars genuinely in sync — an edit made on either side reaches the other automatically.
Illustration: a new meeting added in Google Calendar appears on the iPhone calendar, and a private dentist appointment added on the iPhone shows up in Google Calendar only as “Busy”.
What “two-way” actually means here
Create an event in Google Calendar and it appears in iCloud. Create one in iCloud and it appears in Google. Change the time, retitle it, or cancel it on either side, and the other side updates too — usually within minutes, not the up-to-24-hour lag of a subscribed read-only feed.
Deletions are handled the same way, with a safety net: every change is logged, and anything can be undone if a sync ever does something you didn't expect.
What happens if you edit the same event on both sides
If an event is changed on Google and iCloud before the next sync pass catches up, Seam applies a consistent, predictable priority rule rather than trying to guess which edit you "meant" — it isn't a coin flip and it doesn't silently pick whichever synced first. The side that doesn't win isn't lost: its previous content is written to the change journal and can be restored from Undo, the same as any other synced change.
This kind of true double-edit is rare in practice — it takes editing the same event on both calendars in the same short window. If the sync worker or your internet is briefly down, nothing is lost either way — Seam re-checks both calendars on its own schedule and simply catches up on the next pass. The two calendars never have to be online at the same moment; they never talk to each other directly, only through Seam's own servers running continuously in the background.
A shared calendar link isn't the same thing.
Most people's first attempt is exporting or subscribing to a calendar link. It looks like it works — until an edit or a cancellation doesn't show up on the other side.
How it works
Connect Google
Sign in once. Nothing to export, nothing to copy.
Connect iCloud
An app-specific password — not your real Apple ID password — kept encrypted and revocable anytime.
Pick which calendars mirror each other
New events, edits, and cancellations sync both ways, automatically.
Runs on our servers, around the clock. Your phone can be off.
Built to be trusted with your calendar
The permissions, the data handling, and what happens if you ever want out — stated plainly, not buried in the Privacy Policy.
It previews before it acts
Seam previews every first sync: what gets copied, what gets linked, what gets deleted. Every change is logged, and any change can be undone.
We never see your passwords
Google connects through its own sign-in. iCloud connects with an app-specific password — not your real Apple ID password — that you create yourself and can revoke at any time.
Encrypted, and only used to sync
Access tokens are encrypted at rest. Your events are read only to copy them — never sold, never used for ads.
Delete anytime, fully
Deleting your account stops all syncing and removes your data immediately, with the option to also remove events Seam created.
A person replies, not a queue
Support replies within 3 business days. Professional and Team plans get a human response in about 4 hours.
Live system status
Website, web app, and the calendar sync worker — checked live. status.seamcal.com
Simple pricing.
Try it free first.
Every account starts with 5 days of Professional, free. No card needed. Pay yearly and get two months free.
- Up to 3 calendar pairs
- Two-way sync, every 5 minutes
- Undo changes for 90 days
- Up to 10 calendar pairs
- Sync every 2 minutes
- Private events shared as “Busy”
- Undo changes for 180 days
- Everything in Professional
- Team availability at a glance
- Sync every minute
- Undo changes for a year
Prefer we set it up for you? Done-for-you setup, €199 → You just connect your two accounts.
Before
you ask.
What makes this different from a one-way calendar subscription?
A subscription only ever copies in one direction and can lag up to 24 hours. Seam syncs changes both ways, typically within minutes.
What if I edit the same event on both calendars before it syncs?
Seam applies a consistent priority rule rather than guessing. The side that doesn't win is never lost — it's saved to the change journal and can be restored with Undo.
Does it still work if my phone or laptop is offline?
Yes — sync runs on Seam's own servers on a regular schedule, not device-to-device. Both calendars just need to be reachable when the next sync pass runs, not at the same moment as each other.
Will it duplicate my events?
No. Events that already exist on both sides are linked, not copied twice.
What happens if I stop paying?
Nothing is deleted. Your account drops to the free plan, which syncs one way, a few times a day.
Can I undo a change?
Yes. Every change Seam makes is logged and can be reversed — for 90 to 365 days, depending on your plan.
Does Seam read my events?
Only to copy them between the calendars you pick. Never sold, never used for ads or AI training.