Diff MasterAutomatic row alignment
A complete, unique identifier with shared values is used when available. Otherwise rows are compared by position and the result explains the fallback.
Compare data in two Excel sheets for free.
Compare data in two Excel sheets online for free, including populated rows, columns, values, types and saved formulas.
LOCAL WORKBOOKS
Choose two spreadsheet files
Current safety limits: 20 MiB per file, 50,000 data rows and 200 columns per selected sheet.
Choose both files to continueFiles are processed locally in this browser
Free to useRuns locally in your browserFiles are not uploaded or storedNo sign-upPreparing required files for offline use…
How Diff Master compares Excel and CSV files
Excel Compare reads both workbooks in a local browser Worker, detects usable headers, aligns rows automatically and compares data in the selected Excel sheet pair.
- Choose an original and changed XLSX, XLS or CSV file, then select one worksheet from each workbook.
- Start the comparison. Diff Master automatically aligns columns by usable headers and rows by a stable unique identifier when one is available.
- Filter changed records, inspect values, types and formulas, then download a protected CSV change report.
Complete cell comparison
Every populated cell is included. Stored values, underlying types and saved formula text are compared automatically; formulas are never recalculated.
One worksheet pair
Choose one worksheet from each file. To compare two tabs in one workbook, select that workbook on both sides, then choose a different worksheet for each side. Added or removed rows and columns are included automatically.
Original row
Order ID 1048 · Quantity 12
Changed row
Order ID 1048 · Quantity 18
Expected result: Order ID is detected as a stable identifier, so the record remains aligned and Quantity is reported as one modified numeric cell.
Excel comparison FAQs
Practical answers about how this tool compares content, what stays local and where its current limits are.
Are my Excel or CSV files uploaded?
No. File reading, workbook parsing, row matching, comparison and report generation run in a dedicated Worker inside this browser tab. Diff Master does not upload or store the files or results.
How do I compare data in two Excel sheets?
Choose one sheet on the original side and one on the changed side, then start the comparison. When both sheets have usable headers, columns are aligned by exact header names; populated cells, values, types and saved formulas are then compared locally.
Can I compare two tabs in the same Excel workbook?
Yes. Choose the same workbook for both file inputs, then select the first tab on one side and the second tab on the other. Diff Master compares one selected worksheet pair at a time, so it does not automatically compare every tab in a workbook.
How do I compare two datasets in Excel when rows differ?
Use a complete, unique identifier shared by both datasets, such as an order ID, SKU or email address. Diff Master uses that stable key when available; otherwise it compares rows by position and warns that inserted, removed or reordered rows can create cascading changes.
Does Excel Compare recalculate formulas?
No. Stored cell values, types and saved formula text are compared automatically, but Diff Master does not execute formulas, update cached values or open external references. It also does not compare formatting, macros, charts, pivot tables, Power Query or external connections.