Compute the dates that fall out of an otherwise continuous run; for example, keep the gap and drop the days that were present.
Upload Excel appearance dates and list only the missing days inside an otherwise active run. Sample and blank packs included. Browser-local; no account.
Upload an Excel workbook of identities and dates. Only the missing days in between are exported.
Download the template pack for a filled sample workbook and a header-only blank workbook. Map the required columns, compute in the browser, then export a result sheet. No signup.