If your calendars live on Google, Outlook and iCloud, SYNCDATE is the one we recommend: all three plus any CalDAV server or iCal feed, in one account, one-way or two-way, free for 2 calendars and 1 sync. New syncs copy events as Busy; a two-way Mirror between calendars you own keeps the real titles. We make SYNCDATE, so weigh this as our view; the tools below were checked 8 October 2026.
The tools below are ranked by how well they cover the question in the title: the three providers, one-way and two-way, privacy, and how changes are detected. We checked each competitor's own pages on 8 October 2026 and state only what those pages say. We did not test the other tools ourselves, and where a page says nothing we say so.
The short list
| Tool | Names iCloud? | Direction (per its pages) | Privacy (per its pages) | iCloud change detection (per its pages) |
|---|---|---|---|---|
| SYNCDATE | Yes, over CalDAV | One-way or two-way | Busy copies unless every calendar is yours and the sync is two-way; switchable | Polls about every 15 minutes |
| Hetk | Yes | One-way or two-way per pair | Busy or private copies | Checks every 5 minutes |
| OneCal | Yes | Not spelled out | Control over detail shown | Up to 10 minutes |
| CalendarBridge | Yes | Not spelled out | Busy blocks to full details | Every 5 to 10 minutes |
| SyncThemCalendars | Yes | Both ways or one direction | Hide any field, Busy block | Not stated |
| LeapSync | No, planned | Two-way, one-way | Mirrors say Busy unless you choose details | Not applicable |
Google and Outlook changes reach most of these tools by push notification; iCloud has no push, so every tool on the list finds iCloud changes by polling.
1. SYNCDATE
Best for: people who keep calendars on several providers at once and want one tool, one account and one privacy default for all of them.
SYNCDATE connects Google Calendar and Microsoft Outlook through their own APIs, iCloud, Fastmail, Nextcloud and other CalDAV servers over CalDAV, and any iCal (ICS) feed as a read-only source. Each sync runs one-way or two-way; iCal feeds are always one-way, because a feed cannot be written to. New syncs copy events as Busy, and a two-way Mirror between calendars you own keeps the real titles. You can change either before you start. Delete a sync and you choose whether the copies it created go with it or stay.
Speed. Changes on Google and Outlook usually reach the other calendar in under a minute. iCloud and other CalDAV calendars are polled about every 15 minutes, so a change made on the iCloud side can take that long to show up elsewhere. iCal feeds poll on a schedule. We do not quote a seconds figure, because it depends on the provider and varies from change to change.
Limits. The free plan covers 2 accounts, 2 calendars and 1 sync, which links two of your three calendars. Keeping all three together in one sync takes Plus (up to 5 accounts and 4 calendars per sync); Pro allows up to 20 accounts. See current pricing.
Where it is weaker. Hetk's page states a 5-minute iCloud check, and ours is about 10. iCal feeds can only flow one way. The free plan has one sync.
2. Hetk
Best for: individuals who use exactly Google, Outlook and iCloud and want a narrow tool built around those three. Source: hetk.io, checked 8 October 2026.
Hetk's page names Google Calendar, Microsoft Outlook and Apple iCloud and says it is working on more providers. Direction is chosen per calendar pair, one-way or two-way. For privacy you can replace event details with "Busy" or flag the copies as private. Google and Outlook changes sync "within seconds via webhooks", and for iCloud it says "Apple iCloud has no push": it checks iCloud every 5 minutes, and less often for a calendar that has been quiet.
The plans on its page limit sync pairs (3 on Personal, 8 on Professional), it offers a 21-day free trial with no credit card, and it says team plans do not exist yet. It does not say what happens to the copies when you delete a single sync; deleting your account leaves already-synced events in place as regular events.
3. OneCal
Best for: people who also need CalDAV servers beyond iCloud, or who want to try a tool through a trial before committing. Sources: onecal.io and its pricing page, checked 8 October 2026.
OneCal's pages name Google Calendar, Outlook and iCloud Calendar, and its FAQ says CalDAV servers such as Fastmail, Nextcloud and Zoho work. It describes syncing as automatic and "real-time", and states that "iCloud Calendar and CalDAV calendar updates take up to 10 minutes to reflect on the other calendars". The pages we read do not spell out one-way versus two-way. You control how much detail the copies show, and when you delete a sync you can choose to delete the clones it created.
There is no permanent free plan: the pricing page offers a 14-day trial with no credit card, and plans are capped by number of calendars (2, 5 and 50).
4. CalendarBridge
Best for: people who want to choose exactly which details are shared, or who use Microsoft 365 for Business. Sources: calendarbridge.com and its pricing page, checked 8 October 2026.
CalendarBridge lists Google Calendar, Microsoft 365 for Business, personal Microsoft accounts and iCloud, and says other providers can be synced through an .ics link. It notes that Microsoft 365 personal and family plans have no Internet-accessible calendar and cannot be supported. You can share anything "from simple busy blocks to full event details". It says Google and Microsoft changes typically propagate "within a minute or two", and that iCloud and .ics calendars sync every 5 to 10 minutes.
Its FAQ says that when you delete your sync connections it removes the event copies it created. It offers a trial with no credit card (length not stated on the pages we read); we did not find a free plan. Direction is not spelled out on those pages.
5. SyncThemCalendars
Best for: people who want to hide individual fields on the copied events. Source: syncthemcalendars.com, checked 8 October 2026.
Its FAQ lists Google Calendar, Microsoft Outlook / Office 365 and Apple Calendar (iCloud). You can mirror events both ways or copy in one direction, and you can hide the details of any field in the copied event, which turns it into a "Busy" block. The only speed claim we found is that free/busy times are copied "in real time"; it gives no interval for iCloud.
There is no free plan: it offers a 14-day free trial with no credit card, and paid plans are limited by the number of calendar syncs (5, 16 or 36). The page does not say what happens to copies when you delete a sync.
6. LeapSync (Google and Outlook only)
Best for: people who only need Google and Outlook and care most about stated speed. It does not answer the iCloud question today. Source: leapsync.app, checked 8 October 2026.
LeapSync's page covers Google and Microsoft 365 / Outlook.com accounts, and says two-way iCloud / CalDAV sync is "planned for v2". Two-way is the default, with one-way, busy-block or full-detail modes per pair, and its page says mirrors say "Busy" by default. It states changes are "typically under 5 seconds end-to-end via push notifications from Google and Microsoft", with an hourly safety sweep. It offers a 14-day trial with no card. On cancellation, its mirror events stay in your calendar and you can keep, delete or hide them.
What to check before you choose
- Direction. One-way copies from a hub to the calendars that need to see it; two-way keeps every calendar a full copy. A tool whose pages never say which it does is worth a question before you pay. One-way vs two-way, explained.
- Privacy default. Does a copy show "Busy" unless you opt in, or full details unless you opt out? Ask whether the default changes with the kind of sync: in SYNCDATE, new syncs copy events as Busy, and a two-way Mirror between calendars you own keeps the real titles. See privacy in calendar sync and whether it is safe to give a calendar app access.
- Webhook or polling, per provider. Google and Outlook can push changes to a tool, so those usually arrive in under a minute. iCloud and other CalDAV servers have no push, and iCal feeds are plain files, so a change there waits for the next poll. Ask for the interval, not the word "real-time".
- What happens when you delete a sync. Some tools remove the copies they made, some ask, and some leave them in place. Read this before you build anything you may later undo.
- Your plan's cap. A free plan that covers two calendars cannot join three. Check calendars per sync, not just calendars in total.
For how change detection works under the hood, see how calendar sync works.
How SYNCDATE handles each provider
| Google Calendar | Microsoft Outlook | iCloud and other CalDAV | iCal feed | |
|---|---|---|---|---|
| Connection | OAuth 2.0 | OAuth 2.0 (Microsoft Entra ID) | App-specific password or server credential | Feed URL |
| Direction | One-way or two-way | One-way or two-way | One-way or two-way | One-way (source only) |
| How changes are found | Push notifications | Graph change notifications | Polling, about every 15 minutes | Polling, on a schedule |
| Speed | Usually in under a minute | Usually in under a minute | Up to the next poll | Up to the next poll |
| Recurring events | Full RRULE sync | Pattern and RRULE conversion | VEVENT and RRULE sync | Parsed from the feed |
Outlook is connected through the Microsoft Graph Calendar API, not through an ICS import. Recurrence patterns and Windows-to-IANA time zones are converted both ways, and all-day events are normalised. Some Microsoft 365 organisations require admin consent before a third-party app can read calendars. Step by step: how to sync Google Calendar with Outlook and two-way sync between Outlook and Google.
iCloud, Fastmail and Nextcloud are CalDAV calendars, so they are writable and can take part in two-way syncs. iCloud requires an app-specific password with two-factor authentication turned on. CalDAV has no universal push system, so SYNCDATE polls these accounts about every 15 minutes using sync tokens where the server supports them and ETag comparison where it does not.
iCal feeds are read-only by specification, so SYNCDATE only ever reads them, comparing hashes of each event between polls to find creates, updates and deletes. Paste the feed URL, pick a writable Google, Outlook or CalDAV calendar as the target, and the events appear on that calendar as real events. That differs from subscribing to the feed inside Google Calendar, which refreshes only every 12 to 24 hours and shows the feed as a separate overlay.
A worked setup: work Outlook, personal Google, family iCloud
Connect all three accounts, create one two-way sync with the three calendars in it, and set it to show "Busy" before you save. If all three are calendars you own, SYNCDATE would otherwise keep original titles in a two-way mirror, which you may not want on a work calendar your colleagues can read. With Busy set, your work calendar shows personal and family time as busy blocks and nobody sees titles you did not choose to share. This is three calendars in one sync, so it needs a plan that allows 3 or more calendars per sync (Plus allows 4).
On the free plan, pick the two calendars where double-booking costs you most and link those; a team iCal feed can be added as a third source on a paid plan.
Related reading: how to sync Google Calendar with Outlook, two-way sync between Outlook and Google, how calendar sync works.
Frequently Asked Questions
What is the best tool to sync Google Calendar, Outlook and iCloud together?
It depends on the calendars you keep. If you need Google, Outlook and iCloud plus Fastmail, Nextcloud or an iCal feed in one account, with privacy-first defaults, SYNCDATE is the one we recommend, and we make it, so weigh that as our view. If you only use Google, Outlook and iCloud, Hetk, OneCal, CalendarBridge and SyncThemCalendars all name those three providers on their own pages. Each is described above, with the date we checked.
Does iCloud sync in real time?
No tool can offer that for changes made inside iCloud. iCloud Calendar is reached over CalDAV, which has no push notifications, so a tool has to ask iCloud whether anything changed. SYNCDATE polls CalDAV accounts about every 15 minutes. Hetk says it checks iCloud every 5 minutes, CalendarBridge says 5 to 10 minutes, and OneCal says up to 10 minutes. Changes that start in Google or Outlook are picked up much sooner, usually in under a minute, and are then written to iCloud.
Can I sync Google, Outlook and iCloud for free?
Partly. SYNCDATE's free plan covers 2 accounts, 2 calendars and 1 sync, with no credit card and no trial that turns into a charge, so it links two of your three calendars. Joining all three in one sync needs Plus, which allows up to 4 calendars per sync. See current pricing. Hetk, OneCal, CalendarBridge, SyncThemCalendars and LeapSync describe trials, not permanent free plans, on the pages we checked.
Is iCloud sync two-way or one-way?
In SYNCDATE, iCloud is a writable CalDAV calendar, so it can take part in two-way syncs with Google and Outlook. Apple requires an app-specific password with two-factor authentication on. If your iCloud calendar also publishes an iCal feed URL, you can instead import that feed as a read-only source.
Does SYNCDATE support Microsoft Outlook?
Yes. SYNCDATE connects to Outlook through the Microsoft Graph Calendar API with two-way sync, change notifications, recurring event conversion and time zone mapping. It is not an ICS import workaround.
Can I sync Google Calendar with Outlook in real time?
Changes usually reach the other calendar in under a minute, because Google sends push notifications and Microsoft sends Graph change notifications. We do not promise an exact number of seconds. See the two-way Outlook sync guide for setup.
What is an iCal feed, and can I sync it two ways?
An iCal (ICS) feed is a URL that publishes events in the iCalendar format. Feeds are read-only by specification, so SYNCDATE can import them into a writable Google, Outlook or CalDAV calendar but cannot write back. The feed is polled on a schedule, not pushed.
Will other people see my private event details?
It depends on the sync. New SYNCDATE syncs copy events as Busy. In a two-way Mirror between calendars you own, the real titles are kept unless you switch the sync to Busy, so set Busy before you link a work calendar that colleagues can read. Read privacy in calendar sync for the options.
What happens to the copied events if I delete a sync?
In SYNCDATE you choose whether the events the sync created are removed or left in place. Other tools differ: CalendarBridge says it removes the copies it created, OneCal lets you delete the clones, LeapSync leaves mirror events in your calendar on cancellation, and some pages say nothing about it.
Does Outlook sync require admin approval?
It depends on your organisation's Microsoft 365 settings. Some tenants require admin consent before a third-party app can access calendars, and you would see a "Need admin approval" screen during sign-in. Your IT admin can approve SYNCDATE for the organisation or for individual users.