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Tools / CSV Dedupe

CSV Dedupe

Drop a CSV file to find and remove duplicate rows. Choose which columns to compare, what to keep, and download the cleaned result.

Runs entirely in your browser

Drop a CSV or TSV file here, or click to select.

.csv, .tsv, .tab · Max 500 MB

How to use CSV Dedupe

  1. Drop your CSV

    Drag a .csv or .tsv file onto the dropzone.

  2. Pick comparison columns

    Use the column picker to choose which columns define a duplicate. By default, every column is compared.

  3. Choose what to keep

    First keeps the earliest occurrence, Last keeps the most recent, None drops every duplicated row entirely.

  4. Download the deduped CSV

    Compare the before / after row counts, preview the result, then click Download.

Frequently asked questions

Does this tool upload my CSV?
No. Every parse, transform, and download runs entirely in your browser using JavaScript and Web Workers. The file never leaves your device — there is no upload endpoint and no server-side processing.
Is the comparison case-sensitive?
Yes — values are compared exactly. If you want case-insensitive deduplication, normalize the casing first with CSV Filter & Transform or a small spreadsheet step.
What does the None keep mode do?
It removes every row that has any duplicate. Use it when a duplicate indicates bad data and you'd rather drop the whole group than guess which row is canonical.
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