Duplicate Line Remover
ProductivityPaste a list of lines and instantly remove duplicates, with options for case sensitivity, trimming whitespace, and sorting — processed locally in your browser.
What counts as a duplicate
By default, two lines are treated as duplicates only if they match exactly, character for character. Since real-world lists are rarely that clean, this tool adds a few configurable rules on top: a case-insensitive option treats "Email@site.com" and "email@site.com" as the same line, and a trim-whitespace option ignores leading or trailing spaces that would otherwise make two visually identical lines register as different. Turning both on catches the vast majority of accidental duplicates that creep into lists pasted together from multiple sources.
Why use a dedicated tool instead of a spreadsheet
Spreadsheet software can remove duplicates too, but it means importing the list as data, running a "remove duplicates" command buried in a menu, and exporting it back out — a lot of steps for something that's really just a text operation. This tool skips all of that: paste a list, get unique lines back immediately, with no file import or export required and no risk of a spreadsheet's autoformatting (turning a number-like string into scientific notation, for instance) silently altering your data along the way.
Common use cases
Marketers cleaning an email list before a campaign use it to strip out repeated addresses that crept in from merging multiple sign-up sources. Developers use it to deduplicate a list of URLs, log lines, or config values pasted from different files. Researchers and data analysts use it as a quick first pass on messy pasted data before it goes into a proper spreadsheet or database, and anyone consolidating notes, bookmarks, or a to-do list from several sources uses it to collapse repeated entries into one clean list.
Tips for cleaner results
Turn on the case-insensitive and trim-whitespace options unless you have a specific reason not to — most accidental duplicates in real lists come from inconsistent capitalization or a stray trailing space, not truly distinct entries, so leaving these off tends to under-remove. If you also want the output in a predictable order rather than the original paste order, the sort option arranges the deduplicated list alphabetically, which is often easier to scan and verify than the order lines happened to be pasted in.
How to use Duplicate Line Remover
- 1Paste your list, one item per line.
- 2Toggle case-sensitivity, trimming, and sorting as needed.
- 3Copy the deduplicated result.
Frequently asked questions
Is my list uploaded anywhere?
No — deduplication happens entirely in your browser using JavaScript. Your list is never sent to a server.
Does it treat 'Email@site.com' and 'email@site.com' as duplicates?
Only if you turn on the case-insensitive option — by default, comparison is exact and case-sensitive.
Can it also remove blank lines?
Yes — blank lines are treated the same as any other line, so identical blank lines get collapsed to a single one along with everything else.
Does it keep the first or last occurrence of a duplicate?
The first occurrence of each unique line is kept, in its original position, unless you enable sorting.
Will it tell me how many duplicates were removed?
Yes — the tool shows a count of how many duplicate lines were removed alongside the cleaned result.
Can I use this on a large list, like thousands of email addresses?
Yes, since processing happens locally in your browser rather than on a server, there's no practical size limit for typical list sizes.