CSV Duplicate Row Remover
Remove duplicate rows from a CSV in your browser, with optional case-insensitive and whitespace-trimmed matching.
Pure browser JavaScript. CSV parsing by PapaParse (MIT), self-hosted.
How to use this tool
- Paste CSV or upload a .csv file with a header row.
- Optionally enable Ignore case or Trim whitespace for looser matching.
- Click Remove duplicates, then Copy or Download.
Remove duplicate rows from a CSV in your browser, with optional case-insensitive and whitespace-trimmed matching.
How it works
This tool removes duplicate rows from a CSV file, keeping only the first occurrence of each unique row. It runs entirely in your browser — no data is uploaded.
Paste or upload your CSV. Options include case-insensitive matching (so ACME and acme count as the same value) and whitespace trimming (so a value with extra spaces matches one without). The header row is preserved and excluded from deduplication.
Use this after merging data from multiple sources, cleaning up exported lists, or removing accidental duplicates before importing into a database or mailing list.
The output preserves the column structure and the order of first-seen rows. A count of removed rows is typically shown so you know how many duplicates were found.
Worked example
Remove duplicate email addresses from a mailing list CSV
- Upload the CSV containing the email list.
- Enable case-insensitive matching (emails are case-insensitive by convention).
- Enable whitespace trimming to catch entries with accidental spaces.
- Click Remove Duplicates.
- Download the deduplicated CSV.
A CSV where each email address appears only once, with duplicate rows removed.
Common mistakes to avoid
- Not enabling case-insensitive mode for columns like email or name, leading to duplicates being missed.
- Expecting column-based deduplication (e.g., unique by email only) when the tool compares entire rows.
- Running deduplication before fixing typos — slightly misspelled duplicates will not be caught.
Key terms
- Duplicate row
- A row where every column value matches another row's values exactly (subject to matching options).
- Case-insensitive matching
- Treats uppercase and lowercase letters as equivalent when comparing values for duplication.
- Whitespace trimming
- Ignores leading and trailing spaces when comparing values, so a padded value and a clean value are considered the same.
Frequently asked questions
- What counts as a duplicate?
- A row is a duplicate when all of its column values match an earlier row (after optional trim/case folding). The first occurrence is kept.
- Is anything uploaded?
- No — deduplication runs locally in your browser via PapaParse.