Calendar Merger & Conflict Finder

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. 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.