Remove Duplicate Lines Online – Free Dedup Tool

Paste any list and strip out the repeats in one click. This free tool removes duplicate lines online with ignore-case and sort options, and reports exactly how many duplicates it removed.

How to Use the Duplicate Line Remover

Paste your list into the input box — one item per line. Tick Ignore case if entries like "Boston" and "boston" should be treated as the same line; leave it off if casing is meaningful (for example, in passwords or codes). Tick Sort lines if you want the cleaned list in alphabetical order; otherwise the original order is preserved and the first occurrence of each line is kept. Press Remove Duplicates.

The result box reports the headline figure — "3 duplicates removed · 7 unique lines kept" — and shows the cleaned list, ready to copy with the Copy Result button. Trailing spaces are trimmed before comparing, and repeated blank lines collapse into one, since stray empty lines are the most common accidental "duplicates" in pasted lists.

How Deduplication Works

The tool walks through your lines from top to bottom, remembering each line it has seen. The first time a line appears it is kept; every later repeat is counted as a duplicate and dropped.

With ignore-case on, lines are compared in lowercase, so "SEO Tips" and "seo tips" match — but the first version's original casing is what survives. Sorting happens after deduplication, using alphabetical order. The whole operation is linear in the size of your list, so even tens of thousands of lines process instantly.

Worked Example

Input (10 lines):
boston
Denver
boston
Austin
denver
Boston
Seattle
austin
Denver
Miami

The same list gives 2 or 5 duplicates depending on one checkbox — which is exactly why the option exists. Notice that with ignore-case on, the surviving entries keep their first-seen spelling ("boston", "Denver", "Austin"), not a normalised one.

Real Use Cases — Where This Tool Earns Its Keep

The SEO keyword case is the classic: export 5,000 keywords from a research tool, run them through here with ignore-case and sort, and you get a clean alphabetical file in seconds — a job that takes half an hour by hand in a spreadsheet.

Limitations

The tool compares whole lines only: "Boston " (with a trailing space) matches "Boston", but "New Boston" and "Boston" are different lines, and near-duplicates with typos ("Boston" vs "Bostn") are not detected — fuzzy matching is beyond a line deduper. Sorting is plain alphabetical, not natural sort, so "item10" comes before "item2". Extremely large pastes (hundreds of thousands of lines) may be slow on old phones. And remember the tool only shows you the count after running — it cannot warn you before you paste.

Cleanup usually runs in a sequence: fix the paste first with PasteFix, which repairs the spacing and stray line breaks copying introduces, then deduplicate the lines here.

Lists are one kind of transcript; recordings are another. The Silence Chapters tool splits podcasts and meetings at their pauses into clean, exportable clips — the audio equivalent of deduplicating a text file, one honest cut at a time.

Guides for This Tool

Frequently Asked Questions

Related Tools