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ICS Validator & Fixer

Paste or upload any .ics file. Auto-fixes missing timezones, UIDs, line folding, and other issues that break Google Calendar, Outlook, and Apple Calendar imports.

What gets fixed automatically

Missing VTIMEZONE Adds timezone definitions for referenced TZIDs (Asia/Tokyo, America/New_York, etc.)
Invalid Timezone Names Converts aliases like EST, PST, JST to proper IANA names
Missing UID / DTSTAMP Auto-generates unique IDs and timestamps for each event
Line Folding Wraps lines exceeding 75 octets per RFC 5545
Missing Headers Adds VERSION, PRODID, CALSCALE if missing
RRULE Validation Checks recurrence rules for valid FREQ, BYDAY, COUNT, INTERVAL

How to fix a broken .ics file

Most ICS import failures in Google Calendar, Apple Calendar, and Outlook come from four fixable issues: missing timezone definitions, missing UIDs, invalid line folding, or non-IANA timezone names. Here's the full fix in under a minute.

  1. 1
    Paste or upload the file. Drop your .ics file into the editor above or paste the raw calendar contents. Nothing leaves your browser — processing happens entirely on your device.
  2. 2
    Review the automatic fixes. The validator adds missing VTIMEZONE, UID, DTSTAMP, converts timezone aliases (EST, PST, JST) to proper IANA names, enforces RFC 5545 line folding at 75 octets, and adds missing VERSION, PRODID, and CALSCALE headers.
  3. 3
    Preview the week. Switch to the Week Preview tab to verify events land on the correct days and times after timezone correction — a common cause of "events showing on the wrong day" after import.
  4. 4
    Download and import. Click Download to save the fixed .ics. Re-import into Google Calendar (File → Import), Apple Calendar (File → Import), or Outlook (Calendar → Open Calendar → From File).

Common ICS import errors this fixes

  • "Couldn't fetch events" / "Unable to process your request" (Google Calendar) — usually missing or malformed VTIMEZONE component.
  • "Import failed" with no details — typically lines longer than 75 octets without RFC 5545 line folding.
  • Events land on the wrong day — timezone alias like EST or JST used instead of America/New_York or Asia/Tokyo.
  • "An event with this UID already exists" — duplicate or missing UID properties. The fixer auto-generates unique IDs.
  • Apple Calendar silently drops events — missing DTSTAMP properties. Auto-injected during fix.
  • AI-generated .ics files (ChatGPT, Claude, Gemini) — frequently miss UIDs, use wrong timezone formats, or skip line folding. All fixed in one pass.
  • Outlook says "The file is not a valid iCalendar file" — usually missing VERSION:2.0 or PRODID headers.

Frequently asked questions

How do I fix a broken ICS file?

Paste or upload your .ics file into the editor above. The validator automatically detects and fixes missing VTIMEZONE, UID, DTSTAMP, line-folding issues, and invalid timezone aliases that cause Google Calendar, Apple Calendar, and Outlook to reject the file. Download the corrected file and re-import.

Why does Google Calendar say "Import Failed" for my ICS file?

Google Calendar enforces strict RFC 5545 validation. The most common causes are lines longer than 75 characters without line folding, missing VTIMEZONE definitions, missing UID or DTSTAMP properties, and incorrect date formatting. This validator auto-fixes all of them.

Is this ICS validator free and private?

Yes. It's completely free, no signup required. All processing happens in your browser via JavaScript — your calendar data is never uploaded to any server, logged, or analyzed.

Can I fix ICS files generated by AI like ChatGPT or Claude?

Yes. AI-generated .ics files frequently have issues — missing UIDs, non-IANA timezone names, improper line folding, missing DTSTAMP. This validator was built specifically to catch and auto-fix those patterns in a single pass.

What's the difference between this and other ICS validators?

Most online ICS validators only report errors — you still have to fix them yourself. This tool auto-fixes the common problems (timezones, UIDs, line folding, headers) in one click, then lets you preview the resulting week before downloading.

Does it handle recurring events and RRULE?

Yes. The validator checks RRULE properties for valid FREQ, BYDAY, COUNT, and INTERVAL values, and flags malformed recurrence rules so you can correct them before import.