Remove Duplicate Lines Online — Free Tool
Clean up massive lists or text blocks by stripping duplicate lines while preserving original ordering.
Input lines 5
Unique 2
Removed 3
Preserves original order (keeps the first occurrence).
Privacy note: All processing happens entirely in your browser. No data is sent to our servers.
About this tool
Duplicate lines clutter logs, CSV exports, and email lists. This tool removes repeated lines while optionally preserving first or last occurrence order.
Case-sensitive and trim options control whether 'Apple' and 'apple' count as duplicates.
Common use cases
- Deduplicating email or URL lists
- Cleaning merge-conflict markers from logs
- Shrinking stack traces for tickets
- Preparing unique keyword lists for SEO
How to use
- Paste multiline text into the input.
- Enable trim or case options if needed.
- Run deduplication and review line count reduction.
- Copy the unique-line output.
This page is available at /tools/remove-duplicate-lines/.
Understanding the result
- First occurrence is usually kept; later duplicates drop.
- Empty lines may count as lines—trim option collapses whitespace-only duplicates.
- Order of surviving lines matches first-seen order in original text.
- Very large lists process in memory—split huge files if the tab slows.
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FAQ
Keep first or last duplicate?
Most tools keep first occurrence. Check toggle if last-wins is offered.
Case sensitive dedupe?
Toggle off to treat 'Test' and 'test' as the same line.
Sort after dedupe?
Use the sort-lines tool separately if you need alphabetical order.
Privacy?
Processing is local; lists are not uploaded.