Remove Duplicate Lines
Dedupe a list with case and whitespace controls.
Use Remove Duplicate Lines when a pasted list has repeated rows and you only want one copy of each exact line. The tool trims trailing whitespace before comparing, keeps the first occurrence, and can preserve original order or sort the unique result. Matching is case-sensitive and leading whitespace still matters, so use Case Converter first when “Apple” and “apple” should collapse together.
Part of: Text Cleanup Tools
How to use
- Paste one item per line into the input area.
- Leave Preserve original order on when the first occurrence should stay in place.
- Turn Preserve original order off when sorted unique output is preferred.
- Review the input, output, removed count, and unique rate.
- Use Case Converter first when case-insensitive dedupe is the goal.
Examples
What users are actually trying to do
- ▸ Clean email lists, tag lists, keyword lists, or copied rows.
- ▸ Collapse repeated entries while keeping first-seen order.
- ▸ Create a sorted unique list from pasted text.
- ▸ Prepare import files where duplicate values cause clutter.
- ▸ Remove accidental repeats from notes, logs, or scraped text when repetition has no meaning.
Common mistakes
- ! Expecting case-insensitive matching without normalizing case first.
- ! Assuming leading whitespace is ignored.
- ! Removing duplicates from logs where repeated lines indicate frequency.
- ! Expecting fuzzy or near-duplicate detection.
- ! Assuming sorted output uses the same collation as Sort Lines.
Before you use the result
Word tools can narrow options, clean text, or show patterns, but they do not know the rules of every puzzle, class assignment, publication style, or house dictionary. Check the result against the context where you plan to use it.
For learning, review why a result matched instead of copying the first answer. That keeps the tool useful as practice, not only lookup.
Limitations
- · Matching is case-sensitive.
- · Only trailing whitespace is trimmed before comparison.
- · Leading whitespace and Unicode normalization differences still matter.
- · No fuzzy, near-match, or Levenshtein-style dedupe.
- · No keep-last or show-removed-lines mode in the current UI.
Next up
Frequently asked questions
› How do I remove duplicate lines from text? How-to
Paste one item per line, then copy the output after the duplicate-line remover keeps the first unique occurrence. The tool reports how many lines went in, how many came out, and how many duplicates were removed.
› Is Remove Duplicate Lines case-sensitive? Edge case
Yes, the current Remove Duplicate Lines tool is case-sensitive, so capitalization changes matching behavior during comparisons. “Apple,” “apple,” and “APPLE” are treated as different lines. To approximate case-insensitive dedupe today, convert the list to lowercase with Case Converter before removing duplicate lines.
› Does the duplicate line remover trim whitespace? Definition
The tool trims trailing whitespace before comparing lines, but it does not remove leading whitespace. That means “apple” and “apple ” match, while “ apple” and “apple” remain different. This distinction matters for indented lists and copied tables.
› Does Remove Duplicate Lines keep the first or last copy? Comparison
The tool keeps the first occurrence of each unique line and removes later exact matches. It does not currently offer a keep-last mode. Preserve-order mode keeps first occurrences in their original positions; sorted mode sorts the kept unique lines after dedupe.
› Can I sort unique lines after removing duplicates? How-to
Yes, turning off Preserve original order returns the kept unique lines in sorted order after dedupe. The sort uses the default JavaScript string comparator, which can differ from the Sort Lines tool for case and diacritic edge cases. Use it for quick sorted uniques, then review.
› Why did two identical-looking lines not dedupe? Troubleshooting
Two lines can look identical but differ by case, leading spaces, or Unicode composition under the hood. The current tool trims trailing whitespace only and does not normalize Unicode. Check capitalization, indentation, and accented characters when duplicates appear to remain.
Tips & related reading
See the Text Cleanup Tools hub →Tips & how-tos
Relevant links
Related tools
Sort Lines
Sort pasted lines alphabetically, reverse alphabetically, by length, or numerically, with an optional case-sensitive alpha sort.
Reverse Text
Reverse pasted text by character order, word order, or line order, with copyable output and a simple palindrome hint.
Case Converter
Convert pasted text between uppercase, lowercase, Title Case, sentence case, camelCase, snake_case, kebab-case, and CONSTANT_CASE.