Calendar Conflict Finder
Find overlapping events in an ICS calendar. Choose event series and see when each clash starts and how long it lasts.
How can I find clashes in a recurring calendar?
Open or paste an ICS calendar and choose a local analysis range. The tool expands supported recurrence rules, additions, exclusions and individual moved or cancelled instances. Select event series, inspect their time zones and compare overlapping occurrences. Cancelled and transparent events do not block time; touching endpoints are not conflicts. Download the agenda, conflict report or original source.
Find the time that overlaps.
Bring your calendar. See the clashes, then inspect the details.
Dates in the preview range are inclusive. Local timestamps use YYYY-MM-DDTHH:mm; time zones use IANA names such as America/Toronto.
Your explanation and report will appear here.
Three simple steps
How to use Calendar Conflict Finder
Enter a time, recurrence rule or local calendar file.
Choose the relevant date range and inspect the explanation or overlaps.
Download the report and save a project to reopen your inputs.
Common questions
Good to know
Understand the result.
Keep the original.
Is this tool free, and are my files uploaded?
This tool is free with no account required. The work happens in your browser. Your input and files are not sent to a processing server.
What are the limits and details?
Calculations run in a cancellable browser worker. Time-zone offsets use this browser's installed database unless an imported calendar supplies its own VTIMEZONE. Save a local project file to retain your inputs; files are not uploaded and invitations are not sent.
Up to 1 million characters, 200 event components, 20 embedded time zones, 366 analysis days, 50,000 recurrence candidates, 5,000 occurrences and 10,000 overlaps. EXRULE, RDATE periods and range-based overrides require conversion to explicit dates or individual overrides. Alarms and remote resources are never executed.