Comparing two excel files content

The built-in route is the one described above: keep both files in OneDrive, select them under My Files, and use Copilot > Compare files if your Microsoft 365 tenant exposes that option.

For cases where the workbooks are sensitive and cannot be uploaded, or the Copilot comparison option is unavailable, I built a free browser-local alternative for the narrower task of comparing two versions of the same .xlsx workbook:

https://workbookdiff.com/compare-excel-files-without-uploading/?utm_source=microsoft_techcommunity&utm_medium=community_reply&utm_campaign=workbookdiff_validation&utm_content=copilot_compare_thread_4411585

Disclosure: I built WorkbookDiff. The workbook bytes stay in the browser. It compares coordinate-aligned stored values and formula expressions, worksheet additions/removals/visibility, hidden rows/columns, and used-range changes, with a filterable CSV difference report.

It is not a general reconciliation or AI summary tool: no .xls/.xlsm/.xlsb or CSV input, no reordered-row or key-based matching, formatting, charts, pivots, macros, recalculation, or forensic audit trail.