CSV Deduplicator
Remove duplicate rows from CSV data based on a specific column. Keep only unique values for cleaner datasets — local processing, free, no signup.
How to Use the CSV Deduplicator
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Frequently Asked Questions
How does deduplication work?
Select the column to check for duplicates. The tool keeps the first occurrence of each unique value in that column and removes subsequent duplicates.
Can I deduplicate based on multiple columns?
No — one column per run. To match on combined values, build a single key column upstream first, then deduplicate on it.
Does it preserve the original row order?
Yes. The first occurrence of each duplicate is kept. Subsequent duplicates are removed. The output maintains the original order of first appearances.
How are duplicates detected?
Exact string matching by default. Whitespace differences may cause false non-matches. Trim spaces before deduplicating for best results.
When using CSV Deduplicator, is my CSV data stored?
No. All processing happens locally in your browser. No CSV data is sent to any server.
What does the Default preset remove exactly?
Its 5 rows deduped on the name column collapse to 3 (John, Jane, Bob) — the two repeat rows drop, first occurrences kept in order. Matching is exact and case-sensitive: John and john count as different.
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Last updated October 2026