How to validate an iCal or iCalendar (.ics) file

If you searched for “iCal validator”, you’re almost always trying to validate an iCalendar file — usually a file ending in .ics.

On CorrectICS, the terms “iCal validator,” “iCalendar validator,” and “ICS validator” describe the same CorrectICS validator.

To validate and repair a real file, upload it to: /fix.

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What does an iCal validator check?

iCal / iCalendar validators typically check:

• required iCalendar structure and event blocks
• missing required fields (DTSTART, UID, VERSION, etc.)
• timezone correctness (TZID/VTIMEZONE) and DST behavior
• formatting issues that cause silent import failures

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If your problem is “wrong time” after import

Wrong-time imports usually mean your .ics contains a timezone mismatch.

Start here:

• Fix ICS timezone errors (events at the wrong time)

And for the deeper TZID/VTIMEZONE explanation:

• Fix ICS time zone errors (TZID/VTIMEZONE)

Related help articles

ICS validator: validate an ICS file Use the primary validation workflow and fix the first reported error. ICS file errors: choose your symptom Route validation, import, timezone, or duplicate-event symptoms. What is an ICS file? Learn why iCal and iCalendar files use the .ics extension.

Validate your .ics file and see what can be repaired

Review the diagnostics first. When supported issues can be repaired safely, CorrectICS verifies the improved file before offering a download.

Validate my ICS file Back to Help