Remove Duplicate Lines
Remove duplicate lines from any list online. Keeps the first occurrence of each line and preserves the original order.
This tool deletes repeated lines from your text, keeping the first occurrence of each and preserving the original order. Comparison ignores leading and trailing whitespace but is case-sensitive.
Examples
| Input | Output |
|---|---|
| apple banana apple cherry banana | apple banana cherry |
When to use the remove duplicate lines
Deduplication is a routine step before any list becomes data:
- Email and contact lists merged from several sources, where duplicates mean someone receives the message twice.
- Keyword and URL lists exported from different SEO tools with overlapping coverage.
- Log files, where collapsing repeated identical lines makes the distinct errors visible.
- Import files. Duplicate rows violate unique constraints and abort the whole import.
Two behaviours worth knowing. First, the original order is preserved — unlike piping through sort -u, which reorders everything alphabetically. Second, comparison is case-sensitive: Apple and apple are different lines. To catch case variants, run the lowercase converter first, then deduplicate.
Frequently asked questions
Does it preserve the original order of lines?
Yes. The first occurrence of each line stays in place and later copies are removed. The order is never changed — use the sort lines tool if you also want alphabetical order.
Is the comparison case-sensitive?
Yes. "Apple" and "apple" are treated as different lines. Run the text through the lowercase converter first if you want case-insensitive deduplication.
Does whitespace affect matching?
Leading and trailing whitespace is ignored when comparing, so a line with a trailing space still matches its clean twin. Blank lines are always kept.