Automatic 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 Excel and CSV files online.
Choose one sheet from each file. Diff Master compares every populated cell automatically without uploading your files.
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
Runs 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 the complete selected worksheet 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
The only setup is choosing one worksheet from each file. 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 are rows and columns aligned automatically?
When both sheets have usable headers, columns are aligned by exact header names. Diff Master then looks for a complete, unique identifier with shared values on both sides. If none is reliable, it compares rows by position and shows a fallback warning in the result.
What happens when no stable row identifier is found?
The comparison still runs across the complete sheets. Rows are aligned by their position, and the result warns that inserted, removed or reordered rows may 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.
Which spreadsheet features are not compared?
The current version does not compare formatting, conditional formatting, row heights, column widths, charts, images, comments, macros, pivot tables, Power Query or external connections.