A CSV duplicate finder is a free online tool that scans spreadsheet data for repeated rows. Paste or upload your CSV, choose the key columns that define a duplicate (an email column, an order ID, or the whole row), and see every repeated value grouped with its count. Then keep the first occurrence of each and download a clean, deduplicated file.
How do I find duplicates in a CSV file?
Short answer: Paste your CSV or upload the file, press Load columns, tick the columns that define a duplicate, and press Find duplicates. The tool groups every repeated combination, shows how many times each occurs, and lists the row numbers so you can audit the matches. Review the groups, then press Keep first occurrence to drop the repeats.
Use an email or ID column as the key when you want unique contacts, or tick every column when only fully identical rows count as duplicates.
What counts as a duplicate row?
Short answer: Two rows are duplicates when all of your chosen key columns match exactly. Empty cells match other empty cells, and quoted fields are compared by their real value, so Doe, John always equals Doe, John even with different quoting. Tick case-insensitive matching to treat ANA and ana as the same, and keep the whitespace option on to ignore stray spaces.
Matching is deterministic and stable: rows keep their original order, and Keep first occurrence always preserves the earliest row of each group.
How do I remove the duplicates I found?
Short answer: After reviewing the grouped matches, press Keep first occurrence. The tool rebuilds your CSV with one row per unique key combination, preserving headers, column order, and proper quoting. Download the cleaned file or copy it straight into your spreadsheet. Your original input is never modified.
For recurring cleanup jobs, combine this with the CSV Cleaner to also strip empty rows and blank columns in the same pass.
Frequently asked questions
Is this CSV duplicate finder free?
Yes. Scan and dedupe unlimited CSV data with no account and no limits. Everything runs in your browser.
Which columns should I pick as key columns?
Pick the columns that should be unique: an email address for contacts, an order ID for transactions, or a SKU for products. Tick every column only when fully identical rows are the duplicates you want gone.
Is matching case-sensitive?
By default yes: Ana and ANA are different. Tick case-insensitive match to treat them as the same, and keep the whitespace option on to ignore leading and trailing spaces.
Do empty cells count as duplicates?
Two rows with empty key cells match each other. If that creates false positives, dedupe on a column that is always filled, like an ID or email.
Is my data uploaded anywhere?
No. Parsing, matching, and cleaning all happen locally in your browser, including uploaded files.