Is this free to use?
Yes. It is completely free, with no account, no signup, and no usage limits.
Does it work on a phone?
Yes. The page runs in any modern mobile browser, on iPhone and Android alike, with no app to install.
Do I need to install anything?
No. The tool runs entirely in the browser, so there is nothing to download or install.
What does the number in parentheses mean?
It is the total number of times that exact line appears in your input, counting the first one. An item marked (2) appeared twice, so there is one redundant copy to delete.
Are "Apple" and "apple" reported as duplicates of each other?
No, the comparison is case-sensitive, so they are two separate items. If neither is repeated in its own casing, neither is reported at all. Lowercase the list first if case does not matter to you.
Why is a line that looks repeated not showing up?
The two lines differ as strings even though they look the same. Double spaces inside the text, an invisible zero-width character pasted from the web, or different accented forms of the same letter all produce lines that are visually identical but not equal.
Can I find duplicates in one column of a CSV?
Not directly, because the whole line is the comparison key and the other columns will differ. Copy only that column out of your spreadsheet, paste it here as one value per line, and the duplicates will surface.
Does it delete the duplicates for me?
No, it only reports them. Run the same list through Find Unique List Items to get the deduplicated version, and use this tool to see what was collapsed and how often.
Is my data uploaded?
No. The counting is done in the page, so a list of email addresses, invoice numbers, or SKUs stays on your machine.