Check duplicates & blanks
Choose duplicate keys and required columns. Get a review sheet with the original row numbers.
01 Choose files
Your file is ready.
Preview shows up to 8 rows. Review the result before use. Refreshing clears files and results.
How to use this tool
- 01
Choose a file and sheet to check.
- 02
Select at least one required column or duplicate key.
- 03
Save the workbook containing Data and Review sheets.
Before you start
What are the file limits?
Up to 20 files, 20MB each and 50MB total. Spreadsheets: 50,000 rows, 200 columns, 1 million cells. PDFs: 300 pages total. Images: 16 megapixels each. Your device may require smaller files.
Where are my files stored?
File contents are processed in browser memory, without uploads or persistent app storage. Closing or refreshing the tab clears the work; downloaded files remain on your device.
Will spreadsheet data change?
Original files are unchanged. Dates and numbers are exported as displayed text; formulas are not recalculated. Empty rows are omitted. CSV values starting with formula characters such as =, +, -, or @ may receive a leading apostrophe to prevent formula execution. The checker never fixes values or deletes duplicate rows automatically.
How are duplicates and blanks checked?
Multiple key columns form a combined key. Comparison trims surrounding whitespace and is case-sensitive. Rows with blank keys are excluded from duplicate checks. Every row in a duplicate group is reported, including the first. Whitespace-only required values count as missing.