An iCal/ICS validator checks calendar files against RFC 5545, the standard that defines the iCalendar format. Valid ICS files can be imported into Google Calendar, Apple Calendar, Outlook, and virtually any calendar application. Paste your iCal content or upload a .ics file below to check its structure and extract events.
iCal/ICS Content
Validation Checklist
Component Summary
Extracted Events
| Summary | Start | End | Location |
|---|
Example iCal Snippets
Minimal Event
Recurring Event
All-Day Event
How to Use the iCal/ICS Validator
iCalendar (RFC 5545) is the universal standard for calendar file exchange. Whether you are building a calendar export feature, debugging why an ICS file won't import into Google Calendar, or just checking a file a client sent you, this iCal validator catches structural errors instantly.
Step 1: Paste or Upload Your ICS Content
Copy the contents of any .ics or .ical file and paste it into the text area. Alternatively, click "Upload .ics" to load a file directly. You can also click "Load Example" to start with a sample valid iCal file.
Step 2: Click Validate iCal
The validator runs six structural checks based on RFC 5545: VCALENDAR wrapper presence, VERSION and PRODID properties, matched BEGIN/END pairs, valid date/time formats, required component properties, and overall structural integrity. Each check appears in the checklist with a pass or fail indicator.
Step 3: Review the Component Summary and Events
If the file is valid, you will see a component count (e.g., "3 events, 1 todo") and a readable table of extracted VEVENT entries showing summary, start time, end time, and location. This is useful for quickly auditing the content of a large .ics file without opening it in a calendar app.
Understanding iCalendar Structure
Every valid ICS file starts with BEGIN:VCALENDAR and ends with END:VCALENDAR. Inside, the VERSION:2.0 and PRODID properties identify the calendar. Events are wrapped in BEGIN:VEVENT / END:VEVENT pairs. Dates follow ISO 8601 format: YYYYMMDD for all-day events or YYYYMMDDTHHMMSS[Z] for date-time values. The trailing Z indicates UTC timezone.
Common iCal Errors to Watch For
The most frequent issues are: missing VERSION:2.0 (required, not optional), missing PRODID (identifies the software that created the file), unmatched BEGIN/END blocks (common when manually editing), and invalid date formats (e.g., using slashes instead of hyphens). If you export from a custom system, test the output with this iCal validator before distributing the file.
FAQ
What is an iCal or ICS file?
iCal (iCalendar) is a standard format defined in RFC 5545 for exchanging calendar and scheduling data. Files with .ics or .ical extensions use this format and can be imported into Google Calendar, Apple Calendar, Outlook, and most calendar apps.
What does this iCal validator check?
It validates the complete RFC 5545 structure: VCALENDAR wrapper, VERSION and PRODID properties, BEGIN/END pair matching, VEVENT component properties (DTSTART, SUMMARY), date/time format correctness, and RRULE syntax if present.
Is my iCal data private?
Yes, all validation runs entirely in your browser. Your calendar data is never sent to any server. This tool works offline once loaded.
What are the required properties for a VCALENDAR?
A valid VCALENDAR requires VERSION:2.0 and a PRODID property. Each VEVENT component requires at least a DTSTART property. SUMMARY is strongly recommended but technically optional per RFC 5545.
Why does my ICS file fail validation?
Common causes: missing VERSION:2.0 or PRODID, unmatched BEGIN/END pairs, invalid date formats (must be YYYYMMDD or YYYYMMDDTHHMMSS), or unrecognized component types. The validation checklist shows exactly which checks failed.
What component types are supported?
This validator recognizes all RFC 5545 components: VEVENT (events), VTODO (tasks), VJOURNAL (journal entries), VFREEBUSY (availability), VTIMEZONE (timezone definitions), and VALARM (alarms within events).