How to remove duplicate lines
- Paste your list into the box above with one item per line.
- Leave Trim spaces on so hidden spaces do not hide repeats.
- Tick Ignore capitalisation for emails, names and keywords.
- Pick whether the first or last copy stays. Add sorting if you like.
- Copy the clean list or download it as a .txt file.
What this tool gives you
- Case folding so mixed capital entries collapse into one.
- Space trimming that catches invisible duplicates.
- A choice to keep the first or the last copy.
- Optional blank line removal in the same pass.
- Optional natural sorting so item2 comes before item10.
- An exact count of the repeats it removed.
Why remove duplicate lines?
A repeated line in a list is rarely harmless.
- Email lists: some people get your message twice. Complaints rise and your mail may land in spam more often.
- Product feeds: duplicate codes make a database reject the batch or create ghost records.
- Keyword lists: repeats throw off every percentage you work out.
Duplicates build up whenever data comes from more than one place. Someone merges two exports. Someone copies a sheet twice. A form gets a double click. So a cleanup is usually the first step before you can trust any list.
Why trimming spaces matters
The worst duplicates are the ones you cannot see. Take john@example.com and the same address with a space at the end. They look identical on screen. A computer sees two different lines. Data from spreadsheets and web pages is full of these.
That is why trimming is on by default. Turn it off only when spaces carry meaning. Indented code is one example. For everything else, leave it on. Then the tool never says no duplicates exist in a list that clearly has them.
Should you ignore capital letters?
| Data type | Ignore case? |
|---|---|
| Email addresses | Yes |
| Names and keywords | Yes |
| Passwords and API keys | No |
| Code where case matters | No |
With this option on, the line that stays keeps its original capitals. The comparison ignores case. The output does not change it. Want every line in the same case too? Run the result through the case converter.
Keep the first copy or the last?
For a plain list it makes no difference. It matters when the order carries meaning.
- Keep the last in a time ordered log. The newest entry shows the current state.
- Keep the first in a priority list. The top entry should win.
The tool keeps the original order of every line that stays. So the result reads like the input minus the repeats. Turn on sorting only when you want A to Z order. The sort uses natural order. So item2 comes before item10 and not after it.
Remove duplicate lines in real situations
Merge two email lists
Paste both lists one after the other. Turn on trim and ignore case. Every address appears once.
Clean a product code export
Leave ignore case off if your codes are case sensitive. Keep the first copy.
Tidy a keyword research file
Turn on both options and sorting. You get a clean A to Z list ready for planning.
Common duplicate line problems and fixes
The count looks too high
Ignore case may be on for data where capitals matter. Turn it off and run again.
Some repeats survived
The lines may differ by a hidden character such as a tab. Run the list through the text cleaner first.
My items sit on one line with commas
Put each item on its own line first. Replace each comma with a line break in a text editor. Then paste the list here.
Tips before you import a clean list
- Keep a copy of the original list in case you need to check a removal.
- Spot check a few entries in the result before you import it.
Who uses a duplicate line remover?
Email marketers clean subscriber lists. SEO teams tidy keyword lists. Developers dedupe log entries. Shop owners fix product feeds. Teachers clean class rosters copied from two systems.
Related list cleanup tools
Duplicates are one of several problems in messy lists. Drop blank lines here in the same pass. Fix uneven spacing with the whitespace remover. Put the list in order with the text sorter. Count the lines that remain with the line counter.
Your list stays private
The tool works inside your browser. It sends no list to any server. Customer emails and private data stay on your device.