iCloud Calendar Duplicate Cleaner

Why calendars fill up with duplicate events

Duplicate events usually come from importing the same file twice, syncing one calendar through two accounts, or restoring an old backup over a current calendar. The copies look identical in a calendar app, but deleting them one by one is slow and risky: a repeating meeting and one changed occurrence of it can look like duplicates when they are not. This cleaner works on an .ics file, explains every match and lets you decide.

How to get an .ics file from iCloud Calendar

1. On a Mac, open the Calendar app, select the calendar in the sidebar and choose File, then Export, then Export.
2. For a calendar shared publicly from iCloud, open its public link in a desktop browser and save the .ics file.

A2Z Tools does not sign in to iCloud and cannot see or change your account. It only reads the file you choose.

How duplicates are matched

• Same UID. Every calendar event has a unique identifier. Two events with the same UID and the same changed-occurrence date (or neither has one) are copies of the same event. The copy with the highest sequence number, meaning the most recently edited version, is kept; otherwise the first.
• Same time and title. Events with different UIDs are matched only when the start moment, end moment, all-day setting and title are all the same. Titles are compared ignoring letter case, extra spaces and look-alike characters. Times written in different time zones still match when they describe the same moment.

Repeating events only match another repeating event with exactly the same rule and excluded dates. A changed occurrence of a repeating event is never treated as a duplicate of its series, and a series that has changed occurrences is not matched by time and title, so those occurrences can never be left without their series.

Review before anything is removed

Each group shows the copy that is kept and every copy proposed for removal, with its date, time zone, location, UID and sequence number. Untick a copy to keep it. The summary updates as you go and tells you how many events the cleaned calendar will contain.

Download

• The cleaned .ics keeps every time-zone definition, alarm, attendee and custom property of the remaining events. It is read back before download to confirm the count.
• The removal report is a CSV listing each group, the reason, and what was removed or kept.
• Your original file is never modified.

Limitations

• Similar events with a different time or title are left alone on purpose.
• Removing duplicates from an existing iCloud calendar still means deleting that calendar's events or importing the cleaned file into a new calendar yourself.
• Up to 25 MB and 50,000 events.

Privacy

The calendar is processed in your browser and is not uploaded to A2Z Tools.

A2Z Tools is an independent service and is not affiliated with or endorsed by Apple Inc. iCloud, iPhone and Apple are trademarks of Apple Inc.