Find Duplicates
Load any data file to find duplicate rows. Choose which columns to match on, then see every duplicated row sorted by how many times it appears. Export the results or use the Remove Duplicates tool to clean your data. Everything runs in your browser — your data never leaves your device.
Drop your data file here
CSV, TSV, Parquet, JSON, NDJSON, Arrow, Excel or YAML
or click to browse · max 50 MB
How to use the Find Duplicates
- Drag your file onto the drop area, or click it to browse. CSV, TSV, Parquet, JSON, NDJSON, Arrow, Excel (.xlsx or .xls, first sheet) and YAML files work, up to 50 MB.
- All columns start selected. Click a column to leave it out of the comparison. Leave out ID columns, timestamps and anything else that is unique per row.
- Click Find Duplicates. Two rows count as duplicates when every selected column has the same value.
- Read the three counts: total rows, duplicate rows (every row that has at least one twin) and duplicate groups (how many distinct repeated values there are).
- Review the duplicate rows, sorted so the most repeated come first, then click Export duplicate rows to save them in the same format as your input. YAML input is saved as CSV.
Worked example
A contact list exported from a CRM has the same people entered more than once, each time with a new ID. You want to see who is repeated and how often.
Input (contacts.csv)
id,name,email
1,Ana Silva,ana@example.com
2,Ben Ott,ben@example.com
3,Ana Silva,ana@example.com
4,Cara Lee,cara@example.com
5,Ben Ott,ben@example.com
6,Ana Silva,ana@example.comSettings
- Columns selected: name, email (id deselected)
Output (duplicate report)
Total rows: 6 Duplicate rows: 5 Duplicate groups: 2
id,name,email,_dup_count
1,Ana Silva,ana@example.com,3
3,Ana Silva,ana@example.com,3
6,Ana Silva,ana@example.com,3
2,Ben Ott,ben@example.com,2
5,Ben Ott,ben@example.com,2With all three columns selected the tool finds nothing, because every id is different. Matching on name and email only shows that Ana Silva appears three times and Ben Ott twice. Cara Lee appears once, so she is not listed. The _dup_count column says how many times each row's values occur.
Frequently Asked Questions
How do I find duplicates in a CSV file without Excel?
Load the CSV here, choose the columns that define a duplicate and click Find Duplicates. You get every repeated row with a count, and you can export the list. There is no spreadsheet or formula to set up.
Why does it say no duplicates when I can see repeated rows?
Usually because a selected column is different on every row, such as an ID, a row number or a timestamp. Deselect those columns and run it again. Values must also match exactly, so "Ana Silva" and "ana silva " with a trailing space count as different.
What is the difference between duplicate rows and duplicate groups?
Duplicate rows counts every row that has at least one match, including the first occurrence. Duplicate groups counts how many distinct repeated values there are. In the example above there are 5 duplicate rows in 2 groups.
Does this tool delete duplicates?
No. It only reports them so you can check what is repeated before changing anything. To remove the extra copies, use the Remove Duplicates tool for your file format.
Is my file uploaded?
No. The file is loaded and scanned inside your browser tab. Nothing is sent to a server.
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