YOUR SPREADSHEET DATA NEVER LEAVES YOUR DEVICE

ZERO SERVER UPLOAD ARCHITECTURE

At ExcelCompareColumns, we understand that financial reports, payroll sheets, supplier pricing lists, and audit files contain private, highly sensitive business data.

Unlike legacy cloud diff services that require uploading your `.xlsx` files to a remote server, ExcelCompareColumns performs 100% of its parsing, diff calculation, set matching, and report rendering locally inside your web browser using JavaScript Web Workers and SheetJS.

TECHNICAL VERIFICATION

• Open Network DevTools: No HTTP POST or file upload requests occur when loading or diffing spreadsheets.
• Works Offline: Once the page is loaded, you can disconnect your internet entirely and continue diffing files offline.
• No Third-Party Data Selling or Analytics on Spreadsheet Contents.