Drop in a spreadsheet and see every duplicated row — or every duplicated value in one column, like an invoice number or email address. Then download the duplicates, or the file with them removed. Works with .xlsx, .xlsm and .csv.
✓ 100% in your browser — your file never leaves your computer
Duplicates are usually not the only problem.
Open the same file in the full app for an automatic 0–100 quality score — duplicate IDs, missing values, outliers, date errors and inconsistent categories, each with the affected rows one click away. Still without your data leaving the browser.
Excel's Remove Duplicates button compares text exactly — so ACME Ltd, acme ltd and Acme Ltd count as three different customers, and it deletes rows immediately rather than showing you what it found. This tool ignores capitalisation and stray spaces by default (you can turn that off), and always shows you every group before anything is removed. Rows with a blank value in the chosen column are never treated as duplicates of each other.
No. The file is read with your browser's own file APIs and checked by JavaScript running on your machine. There is no server to upload to — this page ships with a Content-Security-Policy that makes your browser block outbound requests. Here's how to verify that yourself, including with your Wi-Fi off.
Tested to 500,000 rows / 38 MB on an ordinary laptop — see the published benchmark. Parsing runs on a background thread, so the page stays responsive while big files load.
If the question is "what changed between these two files" rather than "what's repeated inside this one", use the free compare two Excel files tool — added, removed and changed rows, matched by ID.
← Prism — the review step before you trust the file