Compare two ICS files
Migrating a calendar and the destination already holds some of the events? Load the source and the destination: the tool keeps only what the destination is missing, in a new .ics file ready to import, without creating duplicates. It also flags modified events, internal duplicates and what exists only in the destination.
Source
Drop an .ics file here or
The original calendar: the events to copy.
Destination
Drop an .ics file here or
The calendar that already holds some of the events.
What the tool does
Source minus destination
It extracts the source events that do not exist in the destination, in an .ics file ready to import.
Three ways to recognise an event
By identifier (UID), by content (title, start, end, recurrence) or both: importing one calendar into another often regenerates identifiers, hence the value of comparing content.
Time zones compared in UTC
Two events at the same time expressed in different zones (10:00 Paris, 09:00 UTC) are recognised as identical; Outlook's Windows time zone names are understood.
Modified, duplicates, orphans
It flags events with the same identifier but different content, duplicates in each file and series exceptions that would be imported without their series.
How to use it
Load the source then the destination. The result appears immediately. Choose how to recognise the same event if needed, check the lists, then download the file of events to import.
FAQ
Why do my events appear twice after an import?
Importing an .ics file into a calendar that already holds these events duplicates them when their identifiers differ. Compare first, then import only the difference, to avoid duplicates.
What is the difference between "identifier" and "content"?
The identifier (UID) belongs to each event and follows the original calendar. After going through another service it may have changed: content (title, times) then lets you recognise the same event.
Privacy
Your files stay on your computer: they are never uploaded.