Duplicate Line Remover
Remove duplicate lines from a list, with optional case-insensitive and trim matching.
Free duplicate line remover
A duplicate line remover deletes repeated lines from a list while keeping the first of each. ProseTool's tool removes duplicates instantly, preserves the original order, and offers case-insensitive and whitespace-trimming options to catch near-duplicates — all privately in your browser.
Lists pulled together from several sources almost always contain repeats: duplicate email addresses, repeated keywords, the same URL pasted twice. Finding and deleting those by hand is painful. This tool collapses every duplicate in a single pass and tells you exactly how many it removed.
How to use the duplicate line remover
- Paste your list into the box above, one item per line.
- Choose whether to ignore case and trim whitespace before comparing.
- Read the counts: lines in, unique lines, and lines removed.
- Copy the de-duplicated list from the lower box.
Features
- Order preserved — the first occurrence of each line stays in place.
- Case-insensitive option to treat differently-capitalised lines as equal.
- Trim option to match lines that differ only by invisible spaces.
- Live counts showing exactly how many duplicates were removed.
- Private and unlimited — nothing is uploaded and there is no size cap.
Benefits of removing duplicate lines
Clean, unique lists are the foundation of reliable data. Duplicates inflate counts, skew analysis, and cause the same person to be emailed twice or the same task to be done again. Removing them is a quick hygiene step that prevents real downstream errors.
Marketers de-duplicate mailing lists and keyword sets, developers clean up logs and configuration, and writers tidy reference lists and glossaries. Because the tool runs locally with no length limit, you can process large lists instantly while keeping sensitive data on your own machine.
Frequently asked questions
Does it keep the original order?
Yes. The first occurrence of each line stays exactly where it was, and later duplicates are removed. The remaining lines keep their original order, so nothing is shuffled.
What does case-insensitive matching do?
With it on, "Apple" and "apple" are treated as the same line, so only the first is kept. With it off, lines must match exactly, including capitalisation, to count as duplicates.
Why trim lines before comparing?
Trimming removes leading and trailing spaces before comparison, so "cat" and "cat " (with a trailing space) are recognised as duplicates. This catches near-duplicates that look identical but differ by invisible whitespace.
Is anything uploaded?
No. The de-duplication runs entirely in your browser. Your list never leaves your device.