Duplicate Line Remover
Use the CaseSwitch Duplicate Line Remover to drop repeated lines from a list while keeping the first copy of each line in its original order. Paste one item per line — emails, tags, URLs, or log output — and copy the unique result. Comparison is case-sensitive and runs in this browser.
Written by the CaseSwitch editorial team. We maintain these tools in the browser so drafts, keys, and images stay on your device.
Last reviewed: 30 August 2026
Processed locally in your browser. Nothing is sent to a server.
Paste or type text to convert. Output stays empty until there is input.
Character count: 0 · Word count: 0 · Line count: 0
Examples
Keep first occurrence, original order
Input
apple banana apple cherry
Output
apple banana cherry
Case-sensitive: Apple and apple both stay
Input
Apple apple Apple
Output
Apple apple
Trailing spaces: first copy kept
Input
apple apple banana
Output
apple banana
Extra blank lines collapse to one
Input
a b
Output
a b
Email list
Input
ada@x.com bob@y.com ada@x.com
Output
ada@x.com bob@y.com
How to use
- Paste the list with one value per line. CSV columns copied from a spreadsheet usually paste this way.
- If spacing looks inconsistent, run the Whitespace Remover first, then paste the cleaned list here.
- Copy the unique lines. First occurrences stay in their original order.
What this tool is for
Repeated lines accumulate in mailing lists, tag dumps, log extracts, and spreadsheet columns pasted as text. This tool deletes later copies of a line and keeps the first occurrence, so the remaining list stays in the order you already had. It is a list cleaner, not a “similar line” merger and not a word-level deduper.
How it works
The text is split on line breaks (Unix or Windows). Each line is compared using the line with trailing spaces removed. The first time that key appears, the original line is kept (including any trailing spaces on that first copy). Later lines with the same key are dropped. Leading spaces are part of the key, so “apple” and “ apple” are different. Empty lines are values too: the first blank line is kept, extra blank lines are dropped.
When to use it
Deduping email lists, unique-ifying a keyword list, cleaning a changelog pasted twice, preparing a column for import, and removing repeated headers from a log extract. Use it when duplicates are exact line repeats and you want to keep original order. Pair with the Whitespace Remover first if trailing spaces or mixed tabs make visually identical lines look different to you but not to the tool.
When not to use it
Do not use it when duplicates are meaningful (repeated log events you still need to count). Use the Word Frequency Counter or a log aggregator for that. Do not use it to merge similar-but-not-equal lines (“NY” vs “N.Y.” or “Apple” vs “apple”). There is no case-insensitive mode on this page: those stay as two lines. Do not use it as a CSV join — it does not parse quoted fields.
How it compares to related tools
The Duplicate Word Finder reports words inside a paragraph, not whole lines. Sort Words Alphabetically can also unique a list if you enable that option, but it reorders. This tool keeps first-seen order. The Whitespace Remover is the usual step before dedupe if spacing is noisy. Remove Line Breaks is the opposite problem (too many breaks, not too many copies).
Common mistakes
Forgetting trailing spaces that make two lines look identical to you — the first copy’s trailing spaces are kept, the second line is dropped only if it matches after trimEnd. Assuming “Apple” and “apple” will collapse (they will not). Expecting fuzzy matching for typos. Deduping a paragraph of prose split into wrapped lines and losing repeated words that happen to sit on their own line.
What “same line” means
Comparison is exact after trailing whitespace is ignored. It is not a locale-aware fold, not a trim of leading spaces, and not a Unicode normalization pass. Invisible characters and different line endings in the source are normalized by the split, but a no-break space is not the same as a regular space. If two lines still both appear, they are not the same key — look for a hidden character or a leading space.
Frequently asked questions
Is comparison case-sensitive?+
Yes. “Apple” and “apple” are different lines. Lowercase the list first with the Lower Case Converter if you want them treated as one.
Are blank lines removed?+
Only extra copies of a blank line. The first blank line is kept; later empty lines are dropped.
Does this change the order of unique lines?+
No. The first time a line appears it stays in that position. Later copies are omitted. If you also need alphabetical order, sort after deduping.
Can I dedupe a CSV?+
You can paste a single column (one field per line). This is not a CSV parser: quoted commas and multi-column rows are treated as whole lines. Split the column out of the spreadsheet first.
Is my list uploaded?+
No. Deduplication runs in this browser. Email lists and logs stay on your device.
Does CaseSwitch upload this text?+
No. Conversion, cleaning, and counting for this page run in your browser. Drafts are not sent to CaseSwitch for processing.
Related guides
Read our original articles on this topic.
Tips
How to Fix Accidental Caps Lock Text
Typed with Caps Lock on? Paste into a case converter — sentence case for prose, lowercase for slugs. No retyping required.
Guides
How to Clean Text Pasted from PDFs, Word, Google Docs, and Chat Apps
Fix hard line breaks, double spaces, hidden formatting, and ALL CAPS paste from PDFs, email, Slack, and Word — with a step-by-step tool workflow that runs in your browser.
Related tools
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Find words that appear more than once in your text.
Whitespace Remover
Collapse extra spaces and trim blank lines.
Remove Line Breaks
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Character Remover
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Remove Text Formatting
Remove common inline formatting markers from text.