Free calendar file tools

Compare Two ICS Calendar Files

Check two calendar exports for added, removed and changed event records. Review migration differences without connecting any accounts.

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Your file

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Waiting for a file

Know what you’re importing.

See event dates, check time zones, and spot warnings before opening your calendar app.

Your calendar account is never connected.

Before and After describe file versions, not connected accounts. Matching uses event IDs and recurrence IDs. Changed IDs appear as added/removed; they do not prove an event was lost. No repair or import is performed.

How to use this tool

Load the original export in Before and the newer export in After.
Compare event records and open a changed record to inspect its fields.
Download the full JSON report for your own review. Neither calendar is modified.

Before you export

Can this prove a migration is complete?＋

No. Apps can rewrite IDs, time zones and properties. Added/removed means an identity is present in only one file. Duplicate identities are marked ambiguous. Verify suspicious records in your calendar app.

What is compared?＋

VEVENT properties and nested components, matched by UID and RECURRENCE-ID including its time-zone parameters. DTSTAMP, LAST-MODIFIED, CREATED and SEQUENCE are ignored. Time-zone definition differences are flagged separately. Other calendar metadata and task records are outside scope.

Are repeating events expanded or times converted?＋

No. Series rules and edited occurrences are compared as stored. Equivalent instants written in different time zones can appear changed. A matching event record can still behave differently if its time-zone definition changed.

Uses the iCalendar standard. Keep the original file and test the output in your receiving calendar app.