VCALENDAR and VEVENT parsing
Unfold content lines, check BEGIN and END structure and count VEVENT components.
Free ICS Calendar File Checker
ICS Calendar File Checker for safer imports Calendar file is checked locally in your browser. No calendar account connection is required.
Upload or paste an .ics calendar file before sharing or importing it. This page combines an ICS File Checker, Calendar Import Checker, VEVENT Checker and RRULE Checker in one browser-side report, so you can review structure, events, time zones, recurrence rules and repair suggestions without connecting a calendar account.
Local calendar file check
Run the ICS Calendar File Checker
Choose an .ics file or paste calendar text. The checker reviews VCALENDAR, VEVENT, UID, SUMMARY, DTSTART, DTEND, DURATION, LOCATION, DESCRIPTION, RRULE, EXDATE, TZID and all-day event patterns in this browser tab.
Calendar file is checked locally in your browser. No calendar account connection is required.
Try sample .ics cases
Calendar file results will appear here
Upload or paste an .ics file to see parse status, event count, calendar name, duplicate UID, missing fields, time problems, all-day format, time-zone risks, RRULE explanation, abnormal events, main issues and repair suggestions.
Calendar file summary
Main issues
RRULE explanation
Abnormal events
Repair suggestions
Local-check boundaries
ICS Calendar File Checker workflow for calendar import QA
Turn a pasted or uploaded .ics file into a local report that explains what may break before import.
Upload and paste flow
Drop an .ics file or paste raw iCalendar text to inspect VCALENDAR and VEVENT structure locally.
Event risk report
Review duplicate UID, missing SUMMARY, DTSTART and DTEND problems, all-day format, TZID warnings and abnormal VEVENT items.
RRULE and fix workflow
Explain RRULE, check EXDATE values and get repair suggestions before you try the file in a target calendar app.
ICS Calendar File Checker features in one page
Use one combined ICS File Checker, Calendar Import Checker, VEVENT Checker and RRULE Checker instead of splitting the job across small pages.
UID and missing-field review
Find duplicate UID values and missing UID, SUMMARY or DTSTART values that can make imported events merge, disappear or look blank.
Date and duration checks
Review DTSTART, DTEND and DURATION values, including events where the end time is earlier than the start time.
All-day event format
Check DATE-based all-day events and warn when DTEND does not look like an exclusive date.
TZID and floating-time risk
Spot TZID values without VTIMEZONE definitions and DATE-TIME values that may import as floating local times.
RRULE and EXDATE explanation
Explain recurrence frequency, interval, count, until and BYDAY values while flagging common RRULE and EXDATE mistakes.
How to use the ICS Calendar File Checker before import
This is a local preflight for iCalendar structure and import risk. The final behavior still depends on the target calendar app.
01
Upload or paste the .ics file
Export the calendar item or feed as an .ics file, then upload it or paste the raw text. The file stays in your browser while the local parser reads it.
- Use the original .ics export when possible
- Keep a copy before editing generated calendar files
02
Review event results
Check whether the file is parseable, how many VEVENT items it contains, which calendar name is present, and whether duplicate UID or missing-field issues appear.
A file can contain valid-looking text but still import badly if UID, DTSTART, DTEND, TZID or all-day values are inconsistent.
Review events 03
Use fixes before retrying
Repair blocking issues first: duplicated UID, missing DTSTART, bad DTEND, invalid DURATION, unknown TZID and broken RRULE or EXDATE values. Then export or paste the updated .ics file again.
- Use UTC times when a feed does not include VTIMEZONE
- Retest recurring events after changing RRULE
- Do not treat local checks as an official import guarantee
ICS Calendar File Checker FAQ
Common questions about local .ics parsing, calendar import risk, recurrence rules, privacy and limits.
What does this calendar file checker validate?
It checks local iCalendar structure including VCALENDAR, VEVENT, UID, SUMMARY, DTSTART, DTEND, DURATION, LOCATION, DESCRIPTION, RRULE, EXDATE, TZID, all-day DATE formatting, duplicate UID values, time ordering and common recurrence-rule risks.
Does this tool upload my calendar file?
No. It reads uploaded or pasted .ics content in your browser. It does not connect to a calendar account, sync events or send file content to a calendar service.
Can this tool guarantee Google Calendar, Apple Calendar or Outlook import success?
No. It performs local structure and pre-import risk checks. Calendar apps can apply their own import rules, time-zone handling and recurrence behavior.
Why does the report warn about duplicate UID values?
UID identifies an event across updates. If separate VEVENT blocks share a UID, an importer may merge, overwrite or skip events, so the ICS Calendar File Checker treats duplicate UID values as a serious import risk.
How does the report interpret all-day events?
It expects all-day DTSTART and DTEND values to use VALUE=DATE or plain YYYYMMDD DATE values. It also warns when an all-day DTEND is not later than DTSTART because DTEND is normally exclusive.
What should I fix first when the check fails?
Start with broken VCALENDAR or VEVENT structure, missing UID, missing DTSTART, invalid DATE or DATE-TIME values, DTEND before DTSTART and RRULE errors. Then review warnings for SUMMARY, TZID, EXDATE and all-day formatting.
Run the ICS Calendar File Checker before importing
Catch VCALENDAR, VEVENT, UID, time-zone and RRULE problems while the .ics file is still easy to fix.
This is a local preflight, not a connection to any calendar account or a guarantee from the target app.