Remove Duplicate Lines
Paste a list and instantly strip out repeated lines, keeping only the first time each one appears.
📖 How it works & FAQWhat this tool does
Remove Duplicate Lines scans your list top to bottom and deletes any line it has already seen, keeping the first occurrence in its original position. It is perfect for cleaning up email lists, keyword lists, log files, CSV columns, URLs, or any pile of text where the same entry shows up more than once. Everything runs inside your browser — your list is never uploaded to a server.
The options explained
Case-insensitive treats Apple, apple, and APPLE as the same line, so only the first one survives. Leave it off when capitalization matters. Trim whitespace strips leading and trailing spaces and tabs before comparing, so "cat" and "cat " count as duplicates — this is on by default because stray spaces are the most common reason near-identical lines slip through. Sort result alphabetizes the surviving lines (A→Z, numbers handled naturally); leave it off to keep your original order.
How to use it
- Paste or type your list into the top box, one item per line.
- Tick the options you want — case-insensitive, trim, and/or sort.
- Press Remove duplicates.
- Read the counter to see how many duplicates were removed and how many unique lines remain.
- Press Copy result to grab the cleaned list, or edit the options and it re-runs automatically.
FAQ
- Which copy of a duplicate is kept?
- The first occurrence, in its original spot. Every later repeat of that line is removed.
- Are blank lines removed?
- Only duplicate blanks. The first empty line is kept; additional empty lines count as duplicates and are dropped.
- Is my data uploaded anywhere?
- No. All processing happens locally in your browser, so nothing you paste ever leaves your device.
- Can it handle very large lists?
- Yes — tens of thousands of lines process almost instantly, since the work is done with a fast in-memory lookup.