Remove Duplicate Lines - Free Online Dedupe Tool

Q: Does it keep the first or the last copy of a duplicate?

Your choice. Remove duplicates (keep first) keeps the earliest occurrence of each line and drops the rest, while keep last keeps the final one. Either way the relative order of the lines you keep stays the same unless you also pick a sort.

Q: Can I make the matching case-insensitive?

Yes. Turn off Case sensitive and Apple, APPLE, and apple are treated as the same line, so only one of them survives. With it on, which is the default, they count as three different lines.

Q: How do I see only the lines that are duplicated?

Set the action to Show only duplicated lines. Instead of removing repeats, the tool lists one copy of each line that appears more than once, which is handy for auditing a list. The opposite option, Keep only lines that appear once, keeps the unique singletons instead.

Q: Will it remove blank lines and extra spaces?

It can. Trim each line strips leading and trailing spaces before comparing, so a space before apple still matches apple, and Remove empty lines drops blank rows entirely. Both are on by default; turn them off if you need to preserve exact spacing.

Action

Sort result

Case sensitive Trim each line Remove empty lines

Input lines (or drag & drop a file) 0 lines

Sample Open file Clear

Output lines 0 lines

Copy Download

About the Remove Duplicate Lines Tool

What does this tool do?

Paste a list on the left and it strips out the repeats, leaving you a clean set of lines on the right. It treats every line as one entry, so it works just as well on a column of emails, a stack of keywords, a log dump, or a few hundred lines of code. The result updates the moment you type or change an option — there's no button to hunt for.

It does more than a plain dedupe, though. You can keep the first or the last time each line shows up, flip it around to see only the lines that were duplicated, or keep just the one-off lines that appear a single time. Matching can be case-sensitive or not, and you can trim stray spaces and drop blank lines in the same pass. Everything runs in your browser, so a long or private list never leaves your device.

How to Use This Tool

Paste your lines. Drop your list into the left box, drag in a .txt or .csv file, or hit Sample to see it work.
Pick an action. Remove duplicates and keep the first or last copy, show only the duplicated lines, or keep only the lines that appear once.
Fine-tune the match. Turn off Case sensitive to treat "Apple" and "apple" as the same, and leave Trim and Remove empty lines on for a tidy result.
Take the result. The right box shows the cleaned list and a count of what was removed — copy it or download it as a text file.

Common Use Cases

Clearing out repeats is one of those small jobs that comes up constantly:

Cleaning a mailing list: Remove duplicate email addresses before an import so nobody gets messaged twice.
Tidying keyword lists: Collapse an SEO or PPC keyword dump down to the unique terms.
De-duping data exports: Strip repeated rows pasted out of a spreadsheet or database.
Finding the repeats: Switch to Show only duplicated lines to audit which entries actually appear more than once.
Merging lists: Combine two lists, then keep only the unique lines across both.

Want to reorder the result too? Try our Sort Lines Alphabetically tool, or browse all our free text tools.

Frequently Asked Questions

Does it keep the first or the last copy of a duplicate?

Your choice. Remove duplicates (keep first) keeps the earliest occurrence of each line and drops the rest, while keep last keeps the final one. Either way the relative order of the lines you keep stays the same unless you also pick a sort.

Can I make the matching case-insensitive?

Yes. Turn off Case sensitive and "Apple", "APPLE", and "apple" are treated as the same line, so only one of them survives. With it on (the default), they count as three different lines.

How do I see only the lines that are duplicated?

Set the action to Show only duplicated lines. Instead of removing repeats, the tool lists one copy of each line that appears more than once, which is handy for auditing a list. The opposite option, Keep only lines that appear once, throws those away and keeps the unique singletons.

Will it remove blank lines and extra spaces?

It can. Trim each line strips leading and trailing spaces before comparing, so " apple" and "apple" match, and Remove empty lines drops blank rows entirely. Both are on by default; turn them off if you need to preserve exact spacing.

Is my data private?

Completely. The whole process runs locally in your browser with JavaScript — nothing you paste is uploaded, stored, or logged, and the tool keeps working offline once the page has loaded.