Calendar Merger & Conflict Finder guide

Create and export

Open the ICS files to combine and choose a date range and display timezone.

Select source events, remove exact duplicates, and review the Conflicts tab.

Export the selected range. The output contains explicit occurrences, without alarms or attachments.

Supported formats and limits

ICS import: up to 10 files, 1 MB each, 5 MB total and 2,000 source events. Supports date-only, UTC, floating and IANA timezone events. Floating times use the chosen display zone. Common daily/weekly/monthly/yearly recurrence, COUNT, UNTIL, BYDAY, BYMONTHDAY, BYMONTH, limited BYSETPOS and EXDATE are supported. Unsupported recurrence, custom timezone IDs, RDATE and recurring overrides are rejected with a message, without importing a partial file. Alarms, attachments, URLs, attendees and custom metadata are omitted. Export contains explicit occurrences in the selected inclusive date range, up to 5,000, rather than unbounded recurring series. A multi-day event overlapping the range is included in full. Ambiguous/nonexistent daylight-saving wall times are rejected; use explicit UTC input for those cases. Calendar conflicts are time overlaps, not travel-time or resource-availability checks. All-day end dates are exclusive. Free events are excluded from conflicts; cancelled source events are omitted. Conflict preview uses the chosen date range and display timezone. Touching end/start boundaries do not conflict. Zero-duration events are not conflicts. All-day conflicts are optional. Displays up to 1,000 overlap pairs, with a truncation notice. Duplicates are exact content matches, not fuzzy title matches.

Local processing

All files, events, names and notes stay in browser memory. No calendar-account connection, upload, external model, background reminders or automatic storage. Refreshing clears the workspace; save an export to keep your work. Exported calendar files require an explicit import into a calendar app; they do not create reservations or synchronize changes.