How to remove duplicates in Excel online
- Choose the file and the sheet. Excel, OpenDocument and CSV files are accepted.
- Choose what makes a duplicate. All columns, for rows that are identical, or only some, such as the email or the customer ID.
- Choose which copy to keep: the first one, or the last one when later rows are more recent.
- Download. You get the clean sheet and, on a separate sheet, every row that was removed with the row it duplicates. Or mark the duplicates without deleting anything.
Private by design
The file is checked by JavaScript in your browser, in a background worker. It is never uploaded, so customer lists, mailing lists and personal data stay on your device. The page only downloads its own code and the open-source SheetJS and PapaParse libraries from this site.
See what you remove before you remove it
Excel’s Data › Remove Duplicates deletes rows in place and only tells you how many went away. Here nothing is lost: the removed rows go to a “Duplicates removed” sheet with their original row number and the row they duplicate, so you can check every decision. If you prefer to decide yourself, “Mark duplicates” keeps every row and adds a duplicate-group number and a status (Unique, Kept, Duplicate) that you can filter in Excel.
Duplicates that Excel does not catch
Excel compares values exactly, apart from upper and lower case. That misses many real duplicates: “ana@example.com” and “ana@example.com ” with a trailing space, “José Pérez” and “Jose Perez”, or the code “00123” in one row and 123 in another. Turn on the normalization options to treat them as the same value. Rows whose compared cells are all empty are never treated as duplicates, so blank lines do not swallow each other.
For near-duplicates with typos, such as “Jon Smith” and “John Smith”, use Find similar duplicates.
Remove the rows of one list that are in another
The second mode answers a different question: which rows of B are not already in A? Typical cases are removing existing customers from a new lead list, removing unsubscribed emails from a mailing list, or keeping only the invoices of this month’s export that were not in last month’s. Choose which columns of B to compare with which columns of A; columns with the same name are paired automatically.
Common uses
- Mailing listsOne row per email address, before importing into a newsletter tool.
- CRM exportsMerge two exports and keep a single record per customer ID, keeping the latest one.
- Orders and invoicesFind invoice numbers entered twice before reconciling.
- Merged filesClean up after merging several Excel files that overlap.
Known limitations
- The file is loaded in memory: hundreds of thousands of rows work on a recent computer; on phones keep it under about 20 MB.
- Duplicates are exact after the normalization options; similar spellings are not detected.
- Values, dates and number formats are kept in the result; fonts, colours and formulas are not (formulas become their values).
- The header must be in the first non-empty row. Password-protected files cannot be opened.