Duplicate Line Remover
Paste any list or text — duplicate lines are removed instantly. Control case sensitivity, whitespace trimming, sort order, and see exactly which lines appear most often.
Options
Matching
Keep occurrence
Sort output
Common Uses
Cleaning Email Lists
Remove repeated email addresses before sending a campaign. Pair with case-insensitive mode to catch '[email protected]' and '[email protected]'.
Deduplicating Keywords
Merge keyword lists from multiple research tools and remove all repeats before uploading to an ad campaign or SEO tool.
Processing Log Files
Extract unique error messages or event types from large server logs to quickly understand the range of issues.
Merging Data Lists
Combine multiple CSV column exports or ID lists and get a clean unique set, ready to paste back into a spreadsheet.
Code & Config Cleanup
Deduplicate import statements, CSS class names, or config entries that have been copy-pasted multiple times.
Vocabulary & Word Lists
Clean up word lists for language learning, Anki decks, or NLP datasets by removing repeated entries.
Frequently Asked Questions
What does a duplicate line remover do?+
It scans your text line by line, identifies lines that appear more than once, and outputs only unique lines — removing every repeated occurrence. You can choose to keep the first or last occurrence of each duplicate and optionally sort the result.
What is the difference between case-sensitive and case-insensitive matching?+
In case-sensitive mode (default), 'Apple' and 'apple' are treated as different lines and both are kept. In case-insensitive mode, they are treated as the same line and only the first (or last) occurrence is kept. The output preserves the original casing of the kept line.
What does 'Trim whitespace' do?+
When enabled, leading and trailing spaces, tabs, and other whitespace are stripped from each line before comparing. So ' apple ' and 'apple' are treated as the same. The output still uses the trimmed version of the kept line, making your list cleaner.
What is the difference between 'Keep first' and 'Keep last'?+
When a line appears multiple times, 'Keep first' retains the earliest occurrence and discards all later ones. 'Keep last' retains the final occurrence and discards all earlier ones. Both produce the same set of unique lines — only the position in the output differs when combined with sort options.
Can I sort the output alphabetically?+
Yes. The Sort option lets you output lines A–Z (ascending), Z–A (descending), shortest-first, or longest-first. Sorting happens after deduplication, so you always get a clean sorted unique list.
What does the Frequency Analysis tab show?+
The Frequency tab lists every unique line alongside the number of times it appeared in the original input, sorted from most to least frequent. This is useful for finding the most repeated entries in large lists like logs, keywords, or email addresses.
Is there a line limit?+
No hard limit — the tool runs entirely in your browser so there is no server. Lists with hundreds of thousands of lines process in milliseconds for most modern devices.
Can I download the cleaned output?+
Yes. Click the Download button below the output to save the deduplicated text as a .txt file to your device.
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