Remove Duplicate Lines
Paste a list and instantly remove all duplicate lines, keeping only unique entries.
How to Use
- Paste your list of lines into the input box.
- Choose case-sensitive or case-insensitive matching.
- Enable "Trim whitespace" to ignore leading/trailing spaces when comparing.
- The deduplicated result appears instantly in the output box.
When to Use This
- Merging two mailing lists exported from different tools leaves overlapping addresses, and case-insensitive matching catches the ones differing only in capitalization.
- Keyword exports pulled from several research tools repeat the same phrases, so deduplicating before import keeps the campaign count honest.
- Log lines gathered from a fleet of servers repeat identical errors, and the removed count tells you how much of the volume was repetition.
- Developers tidying a long block of import statements or identifiers get unique entries without losing the order they were originally written in.
Frequently Asked Questions
About This Tool
Removing duplicates is really a question about equality. Whether Apple and apple are one entry, whether a trailing space matters, and whether the original ordering survives are decisions the tool makes for you. Sorting and dropping neighbors is fast but scrambles the order; keeping the first of each kind preserves it.
This tool takes the second approach. Text is split on newlines and each line is reduced to a comparison key, trimmed when Trim whitespace is on, which it is by default, and lowercased when Case insensitive is on. A set holds the keys already seen, so the first line producing a new key is kept exactly as you typed it and later matches are discarded in original order. The badge reports how many lines were dropped and how many remain, and output refreshes as you type.
Notes & Limits
- Blank lines are compared like any other line, so unless Remove blank lines is on, every blank after the first disappears, not just consecutive ones.
- The line kept is the first occurrence exactly as typed, so with Trim whitespace on the survivor can still carry the leading or trailing spaces it came with.
- Matching is exact across the whole line, so near-duplicates separated by a comma, an accent or a middle initial are treated as distinct entries.
- Deduplication works on whole lines only; repeated words inside a sentence or repeated values within one CSV field are left untouched.