How are duplicates detected?

The tool compares the entire content of each row. Two rows are considered duplicates if every cell matches. By default, comparison is case-insensitive.

Which duplicate is kept?

The first occurrence of each row is kept. All subsequent duplicates are removed while preserving the original row order.

Does it affect the header row?

No. The header row is always preserved and is not included in duplicate detection.

CSV Deduper

Detect and remove duplicate rows from CSV files. Choose which columns to compare for smarter deduplication. Case-sensitive or case-insensitive comparison available. All processing happens in your browser — your data never leaves your device.

Drop files here or click to browse

Supports .CSV (up to 20 files)

Your files are processed entirely in your browser. Nothing is uploaded to any server.

How to Use CSV Deduper

1
Upload your data file
Drag and drop your CSV, JSON, or data file into the upload area.
2
Configure the transformation
Set delimiters, choose columns, or select the output format for your data.
3
Download the result
Click download to save the cleaned or converted data file. Processing runs locally in your browser.

Frequently Asked Questions

Next Steps

Clean up empty rows and whitespace

Convert back from JSON if needed

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