Remove Duplicate Lines
Remove duplicate lines from your text, keeping only the first occurrence.
How to use this tool
- Enter text in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your deduplicated text and the full breakdown beneath it.
Remove duplicate lines from your text, keeping only the first occurrence.
How it works
This tool removes repeated lines from your text, keeping only the first occurrence of each unique line and discarding all subsequent duplicates. The comparison is case-sensitive by default, so 'Apple' and 'apple' are treated as different lines and both retained.
This is useful for deduplicating keyword lists, cleaning up log file excerpts, removing repeated entries from exported CSV or TSV data, and consolidating items that were merged from multiple sources. The original order of the first occurrences is preserved, so you do not need to re-sort after deduplication.
Paste your text and the unique-only version is returned instantly. The tool makes no other changes — spacing, capitalisation, and punctuation within each line are unchanged.
Worked example
Deduplicate a keyword list
- Paste lines (one per line): SEO, PPC, SEO, content marketing, PPC, SEO.
- The tool scans each line in order.
- Second and subsequent occurrences of 'SEO' and 'PPC' are removed.
- Read the deduplicated list.
SEO PPC content marketing
Common mistakes to avoid
- Expecting case-insensitive deduplication — lowercase everything first if you want 'Apple' and 'apple' treated as duplicates.
- Assuming lines with trailing spaces are the same as lines without — they are not; clean whitespace before deduplicating.
- Using this on data where repeated lines are intentional (for example, a log of events that genuinely repeat) — review before discarding.
Key terms
- Duplicate line
- A line in a text file that is character-for-character identical to a previous line.
- First-occurrence preservation
- A deduplication strategy that keeps the first time a value appears and removes all later repetitions.
Frequently asked questions
- Is the comparison case-sensitive?
- Yes — 'Apple' and 'apple' are treated as different lines.