Remove Duplicate Lines
Paste any block of text and instantly remove duplicate lines. Choose whether matching is case-sensitive, whether to ignore whitespace, and whether to keep the first or last occurrence.
Processed locally in your browser.
What does this tool do?
This tool removes duplicate lines from a block of text, keeping only unique lines. It is useful for cleaning up lists, log outputs, CSV data, and any text where repeated entries need to be eliminated.
How to use
- Paste your text into the input area — one entry per line.
- Set the matching options — case-sensitive or case-insensitive, ignore leading/trailing whitespace, and whether to keep the first or last occurrence.
- The deduplicated output and statistics appear immediately below.
- Click Copy to copy the result.
Options explained
- Case-sensitive —
Appleandappleare treated as different lines. - Case-insensitive —
Appleandappleare treated as duplicates. - Ignore leading/trailing whitespace —
"apple"," apple ", and"apple "are treated as duplicates. The original text of the kept occurrence is preserved. - Keep first — the first occurrence of each line is retained.
- Keep last — the last occurrence of each line is retained.
- Remove empty lines — blank lines are excluded from the output.
Example
- Input: apple / banana / apple / orange / banana
- Output (case-sensitive, keep first): apple / banana / orange
- Duplicates removed: 2
Privacy
Your text is processed entirely in the browser. Nothing is transmitted to any server.
Frequently Asked Questions
Is empty-line removal automatic?
No — empty lines are kept by default. Enable the 'Remove empty lines' option if you want blank lines excluded from the deduplicated output.
Is my text sent to a server?
No. All line processing and deduplication algorithms execute client-side directly in your browser. No text or data is transmitted to any external server.
What is the difference between Keep First and Keep Last?
Keep First preserves the earliest occurrence of a duplicated line and removes all subsequent copies. Keep Last preserves the final occurrence and discards previous instances.
How does whitespace ignoring work?
When enabled, leading and trailing spaces or tabs are ignored when checking if lines are identical. The original indentation and formatting of the preserved line are kept intact.