Remove Duplicate Lines
Paste a list and instantly remove duplicate lines — all processing happens client-side in your browser, so your data never leaves your device. Choose case-sensitive or insensitive matching, trim whitespace, and keep the first or last occurrence. Preview changes before applying.
Input Text
Deduplication Options
Select how duplicates should be detected, review the highlighted preview, then click Apply.
Treat uppercase and lowercase as different values — "Apple" and "apple" are kept as distinct lines.
Strip leading and trailing spaces from each line before comparing — " hello " and "hello" count as the same.
When a duplicate is found, keep the last occurrence instead of the first.
Why Use This Tool?
Removing duplicate entries is one of the most common list-cleaning tasks — whether you are deduplicating email lists, cleaning up keyword sets, processing log files, or merging data from multiple sources. This tool applies a line-by-line deduplication algorithm entirely inside your browser. Your data never leaves your device.
Case-Insensitive Matching: Catch duplicates regardless of capitalisation. "ERROR", "error", and "Error" all count as the same entry when case-insensitive mode is active.
Whitespace Normalisation: Invisible leading or trailing spaces often cause duplicates to slip through automated checks. Enable Trim Whitespace to catch entries that differ only in surrounding spaces.
Undo Anything: Every apply action is tracked in a built-in undo/redo stack — click undo to instantly restore the previous text if you applied an incorrect deduplication setting.
Before/After Preview: See a side-by-side diff of your list before committing any changes — every line that will be removed is highlighted in red so you can verify the result before clicking Apply.
Keep First or Last: Choose whether to retain the first or the last occurrence of each duplicate — useful for time-ordered data where the most recent entry is the authoritative version you want to preserve.
How to Use It
- 1
Paste your list into the text area above — one item per line. You can paste from a spreadsheet, a text file, or anywhere else.
- 2
Choose your options: toggle Case Sensitive if capitalisation matters, enable Trim Whitespace to ignore surrounding spaces, and switch to Keep Last Occurrence if you want the last version of each duplicate retained.
- 3
Review the Preview panel. The Before column highlights every line that will be removed in red; the After column shows the clean deduplicated list.
- 4
Click Apply to update the text area with the clean list, then Copy Result to send it to your clipboard.
Frequently Asked Questions
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