Remove Duplicate Lines

Remove Duplicate Lines is a free, browser-based tool built for one job: deduplicate lines with case-insensitive & trim matching, keep first/last, find-only-duplicates and show-unique modes, plus occurrence counts. It is part of ToolsMonk's text tools collection, so you can finish the work without downloading software, creating an account, or jumping between multiple websites.

Common scenarios include de-duplicating a list of emails, urls, or items, cleaning a dataset of repeated rows, and removing repeated lines from logs or exports. The browser-based design means you can switch devices mid-task and pick up right where you left off, whether it's a one-time job or part of a daily workflow.

It is built for getting a real result on the first visit: no learning curve, no account, and the wider ToolsMonk toolbox close at hand.

Remove Duplicate Lines strips repeated lines from a block of text, keeping the first occurrence of each and removing the rest, the quick way to clean a list of emails, URLs, rows, or log lines.

It preserves the original order by keeping each line's first appearance in place, so the list stays as you intended minus the repeats. If you want the result sorted as well, the Text Sorter can sort and de-duplicate together.

A common surprise is lines that look identical but aren't treated as duplicates, almost always because of invisible differences like trailing spaces, tabs, or capitalisation. Enabling whitespace-trimming and case-insensitive matching catches these, which is exactly what you want when de-duplicating things like email addresses where 'A@x.com' and 'a@x.com' should count as one.

Everything runs in your browser, so your data stays private, and the tool reports how many duplicates it removed. Pair it with Text Sorter and Find and Replace in the ToolsMonk text toolkit for full list cleanup.