CSV Duplicate Row Remover

CSV Duplicate Remover - Deduplicate CSV Rows Instantly

The CSV Duplicate Remover identifies and removes duplicate rows from CSV, TSV, and semicolon-separated files directly in your browser. Upload a file, choose whether to match entire rows or specific columns, and download a clean, deduplicated file - no signup, no server upload, fully private. The delimiter is detected automatically.

How do I remove duplicate rows from a CSV file?

Upload your CSV file using the file uploader. All columns are selected by default, so the tool treats rows as duplicates only when every field matches exactly. Deduplication runs automatically as you adjust settings - there is no manual "run" step. As soon as your file is loaded, duplicate rows are removed and the cleaned result is ready to download.

Can I deduplicate based on specific columns only?

Yes. After uploading your CSV, deselect columns you want to ignore from the pill-style column selector. All columns are selected by default; you can use the "Deselect All" / "Select All" toggle to quickly switch between full-row and partial-column matching. Only the selected columns will be compared when determining whether two rows are duplicates. For example, keeping only "email" selected will remove all rows that share the same email address, regardless of differences in other columns. Results update live as you change the selection.

What does "Keep first occurrence" vs. "Keep last occurrence" mean?

When deduplicating by specific columns, multiple rows may share the same key values but differ in other fields. The keep strategy determines which row survives: "First occurrence" retains the earliest row in the file, while "Last occurrence" keeps the most recent one. This option appears automatically when you select partial-column deduplication.

How does the whitespace trimming option work?

By default, the tool trims leading and trailing whitespace from cell values before comparing them. This means " John " and "John" are treated as identical. You can disable this behavior by unchecking the "Trim whitespace when comparing" option if your data relies on exact spacing.

Is my CSV data uploaded to a server?

No. All CSV processing happens entirely in your browser using JavaScript. Your file never leaves your device, so sensitive data like customer records, email lists, or financial information stays private.

What file formats and delimiters are supported?

The tool supports comma-separated (CSV), semicolon-separated, and tab-separated (TSV) files. The delimiter is detected automatically from the first row of your file. Quoted fields, escaped quotes, and multiline values within quoted fields are all handled correctly, as are both Windows (CRLF) and Unix (LF) line endings. The deduplicated file is exported using the same delimiter as the original.

How large can my CSV file be?

Since processing runs in your browser, file size is limited only by your device's available memory. Files with tens of thousands of rows typically process in under a second. For very large files, consider using the "Load all rows" option only when you need to inspect the full dataset.

Can I preview my data before deduplicating?

Yes. As soon as you upload a CSV, the tool displays a table preview showing the column headers and the first 10 rows. You can click "Load all rows" below the table to see the full dataset with scrolling. After deduplication, the table updates to show only the remaining rows.

How do I export the deduplicated CSV?

When duplicates are found, two export options appear automatically: "Download Deduplicated CSV" saves the file to your device with a -deduped suffix, and the copy button copies the entire CSV content to your clipboard for pasting into spreadsheets or other tools.

What happens if no duplicates are found?

If your CSV contains no duplicate rows based on your current column selection, the tool will display a notification letting you know that no duplicates were found. Your data remains unchanged.

Can I use this tool to clean mailing lists or contact databases?

Yes, just upload your contact CSV, select the columns that define uniqueness - such as "email" or "name" + "address" - and remove duplicates in one click. This is useful for cleaning exported spreadsheet data or preparing data for import into CRM systems, email marketing platforms, or databases.