Compare Excel Files — Private, No Uploads
Drop two Excel workbooks and get a 100% private Diff Report showing changed cell values, added/removed sheets, and formula edits — without your data ever leaving your computer.
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This tool runs 100% inside your browser. Both workbooks are loaded directly into your device's memory (RAM) using JavaScript. No data is transmitted to any server, at any point. Not even a filename. You can disconnect from the internet entirely and this tool will still work.
Important: understand what this tool does and does not do
This tool executes a direct cell-by-cell comparison using each cell's address (e.g. A1, B3) as the unique key. It works best when both workbooks share the exact same column and row structure. It does not natively handle dynamically inserted or deleted rows and columns — if a row was inserted in File B, every cell below it will appear as "changed" even if the actual data is the same.
Original File (Base)
The "before" workbook
Drop .xlsx / .xlsm here, or click
Modified File (To Compare)
The "after" workbook
Drop .xlsx / .xlsm here, or click
How it works
What gets reported?
- Cell values that differ between File A and File B (including cells that went from empty to a value, or vice versa)
- Sheets present in File B but not in File A (added sheets)
- Sheets present in File A but not in File B (removed sheets)
What is NOT reported?
- Inserted or deleted rows/columns — the tool compares by cell address, not row position
- Formatting changes (colours, fonts, borders)
- Formula changes where the computed value is identical
What is an Excel file comparison?
An Excel file comparison is a side-by-side analysis of two workbooks that reports what changed: cell-by-cell value differences, formula changes, sheets that were added or removed, and structural differences. The output (usually called a Diff Report) is what you reach for when you need to audit edits, verify a contractor's work, reconcile a month-over-month financial report, or detect tampering in a shared workbook.
SimpleTool compares Excel files entirely in your browser using a SheetJS reader. Source files never leave your device. The comparison is by cell address (A1 in file 1 vs A1 in file 2) — which is fast and reliable but does not detect “moved” data (inserted/deleted rows that shift surrounding cells). Inserted rows show up as changed values for every cell below the insertion.
When do you need to compare two Excel files?
Real situations where a local diff report beats sending the workbooks to a generic cloud comparator.
Auditing changes in a budget or forecast
You sent a budget template to a department head; they sent back an edited version. A diff report shows exactly which cells they changed, by how much, and on which sheet — without scrolling cell-by-cell across two windows.
Verifying a contractor or vendor's edits
A consultant or external analyst delivered an updated version of a model. The diff report makes their changes auditable in 30 seconds: cell-level value changes + formula changes + structural sheet differences in a single report.
Month-over-month financial reports
This month's P&L vs last month's, or this quarter's forecast vs the previous one. The diff highlights the cells that moved — useful for variance analysis or for a board pack that explains exactly what changed.
Validating a data import
You re-ran an ETL pipeline producing an Excel output and want to confirm the new file matches the previous baseline except for the expected delta. The diff shows expected changes (good) and unexpected changes (investigate).
Reconciling supplier price lists
A supplier sends quarterly price lists as Excel files. Diffing this quarter against last quarter exposes every price change, every added or removed SKU, and any silently re-categorised items — without manual VLOOKUP-stitching.
Pre-merge review of two analyst versions
Two analysts forked the same starting workbook to work in parallel. Before merging their changes back together, the diff report shows which cells each one touched so you can resolve conflicts cleanly.
Detecting tampering in a shared workbook
A workbook that should not have changed (an archived close, a signed-off plan) suddenly looks different. The diff report against a clean copy quantifies exactly what was modified — useful for forensic / compliance review.
Regression-testing a spreadsheet model
You updated formulas in a complex model (mortgage calculator, tax planner, sensitivity analysis) and want to confirm the cells that should change have changed and nothing else moved. The diff is your regression test.
How SimpleTool Compares
Each option has a different sweet spot. Here's how they line up.
| Feature | SimpleTool | Office Suite Add-in | Desktop Diff Tool | Cloud Diff Sites |
|---|---|---|---|---|
| Cost | Free | Bundled w/ Office suite | Paid | Free with limits |
| Files stay private (no upload) | Yes | Yes (desktop) | Yes (desktop) | No — uploaded |
| Install required | No (browser) | Yes | Yes | No |
| Cell-by-cell value diff | Yes | Yes | Yes (Pro edition) | Yes |
| Formula diff | Yes | Yes | Yes (Pro edition) | Variable |
| Sheet add/remove detection | Yes | Yes | Yes | Yes |
| Row-insert/delete detection | No (cell-address based) | Limited | Yes | Variable |
| Diff report export | Yes (Excel) | Yes | Yes | Yes |
| Account required | No | Microsoft account | No | Usually yes |
| Works on locked corporate laptops | Yes | Yes if Office installed | No (install needed) | Yes (browser) |
Comparison reflects publicly documented features as of mid-2026. “No (cell-address based)” is an honest limitation: row-insertion detection is genuinely valuable and dedicated diff tools are better at it. For most audit / reconciliation use cases the cell-address diff is enough and runs without install.
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