Check Excel duplicates & blanks

Choose duplicate keys and required columns. Get a review sheet with the original row numbers.

01 Choose files

Drop your files hereor click to choose filesXLSX · CSV · TSV · 20MB per file · 50MB total

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.

Worked example

The values below are fictional examples that illustrate the workflow.

Input and settings

Columns: ID,Name
First data row: 001,Alex
Second data row: 001,Sam
Third data row: 002,(blank)
Duplicate key: ID / Required field: Name

Expected result

First and second data rows: duplicate ID
Third data row: missing Name
Original data appears in Data; findings appear in Review

How to check Excel duplicates and required blank cells →