Find Duplicates in a CSV

duplicate groups · source row numbers · any key columns · case & space options

See your duplicates before you delete them. Pick which columns define "the same record" — the whole row, or just email, or invoice + date — and get every duplicated row back, grouped and numbered, with the line it came from in the original file. When you already know you want them gone, Dedupe does the removing.

How to find duplicate rows

1. Paste the CSV or drop a file. Every column starts ticked, which finds fully identical rows.
2. Untick columns until only the ones that define identity remain — email alone, or order_id + line_no.
3. Read the status line: how many duplicate keys there are, and how many of your rows they cover.
4. Switch the output mode depending on what you need next — a report, a flagged copy of the full file, or a deduped version.

The four output modes

• Only duplicated rows, grouped — a report. Each row carries dup_group, dup_count, and source_row so you can find it in the original file.
• All rows + dup_group / dup_count — your whole file with duplicates annotated. Good for sorting or filtering in a spreadsheet afterwards.
• First of each group — a deduped file that keeps the earliest occurrence.
• Rows that appear exactly once — the opposite view: records with no twin anywhere. Useful for reconciliation, where a row appearing once means something failed to match.

Why duplicates hide

Two rows that look identical on screen often differ by a trailing space, a non-breaking space pasted from a web page, or casing ([email protected] versus [email protected]). Ticking ignore edge spaces and ignore case catches those without changing your data — the comparison is normalised, the output rows are untouched. If you want the file itself cleaned, run Trim whitespace first.

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