Free browser tool
CSV Duplicate Checker
Keep the first occurrence. Preview every decision before you download.
1. Add your CSV
Comma-separated UTF-8 only. Maximum 2 MiB, 20,000 data rows and 200 columns. Quoted commas, line breaks, escaped quotes and a UTF-8 BOM are supported. Convert other encodings to UTF-8 first.
2. Choose how rows match
Comparison is exact and case-sensitive: spaces, leading zeros and text such as 001 are preserved. No trimming or number conversion. Rows with empty keys can match each other.
3. Review and download
Input preview
Rows to remove
Record numbers count CSV records, including a header when present; quoted line breaks do not add records.
Cleaned preview
Each preview shows up to 10 rows. The download includes all kept rows in their original order.
Export is UTF-8 with CRLF record separators. Spreadsheet apps may reinterpret dates or remove leading zeros; use their import dialog and choose Text for identifier columns.
What counts as a duplicate?
With all columns selected, every cell must match. With selected columns, only those keys determine a match; other values on removed rows may differ. The first matching row is always kept. Review the removal preview before exporting and keep a copy of your original file.
Limits
This tool handles comma-separated text files, not XLSX workbooks or semicolon/tab-delimited files. A one-column file is valid CSV. Blank records are retained and must have the same width as other records. Headers do not need to be unique because columns are identified by position.