Paste one item per line, then click Run; the de-duplicated list appears in the output box, ready to copy.
- Drop the list you want cleaned into the input box, one entry per line; existing order is preserved.
- Click Run. The first copy of each exact line is kept; every later repeat is dropped.
- Copy the cleaned list from the output box below. Edit the input and click Run again any time to redo it.
Remove Duplicate Lines
FreetoolOnline Editorial TeamStrip repeated lines out of a text block, right in your browser. Paste your list with one item on each line, then click Run; the cleaned list appears in the output box below, ready to copy.
Key features
- An in-browser text editor (textarea) for pasting your list - no upload, no sign-in.
- Reads your list top to bottom and keeps the first time it sees each exact line, dropping every later repeat.
- The lines that remain stay in their original relative order.
- The cleaned result renders straight into the page, ready to copy.
When to use it
It is a quick way to trim a pasted list of email addresses, tags, or product IDs down to the unique set, or to clean up lines copied from a log file or a spreadsheet column before reusing them.
One thing to know: the comparison is case-sensitive and whitespace-sensitive, so "Apple" and "apple" count as different lines, and a line with a trailing space is different from one without. Run a case converter first if your list mixes capitalization and you want those variants folded together.
Your text stays on your device
Duplicate detection runs locally with plain JavaScript; the text you paste stays on the page and is never transmitted or stored. Leave the tab and nothing remains - no logs, no sign-in.
Related list tools
Need a different list task? The sort text lines tool reorders instead of trimming, and the word counter tallies what is left. A step-by-step walkthrough lives in the Remove Duplicate Lines guide.
Two things people paste that behave differently: blank lines and one property name
Remove Duplicate Lines applies its first-occurrence rule to every line you paste, including two cases that are easy to miss. A blank line counts as a line like any other: paste a list with several empty lines scattered through it and click Run, and Remove Duplicate Lines keeps only the first blank line and drops every later one, exactly the way it drops a repeated word or ID.
One line of text is the exception to that rule. If a line reads exactly __proto__, Remove Duplicate Lines keeps every copy of it in the output instead of dropping the repeats. That is a quirk of how JavaScript handles that one specific property name internally, not a bug in your list - a line reading constructor, toString, hasOwnProperty, or valueOf, which are also built-in JavaScript names, still dedupes normally:
| Line pasted 3 times in a row | Copies kept after clicking Run |
|---|---|
| constructor | 1 |
| toString | 1 |
| hasOwnProperty | 1 |
| __proto__ | 3 |
In practice this only matters if you are cleaning up a list of code identifiers, JSON keys, or config values that happens to include the literal text __proto__ on its own line; every other line in that same list is still deduplicated as expected.
A small worked example
Paste these 8 lines into Remove Duplicate Lines: alice@example.com, bob@example.com, alice@example.com, carol@example.com, bob@example.com, dave@example.com, alice@example.com, erin@example.com. Click Run once, and the output box shows exactly 5 lines: alice@example.com, bob@example.com, carol@example.com, dave@example.com, erin@example.com.
Frequently Asked Questions
What does Remove Duplicate Lines do?
It strips repeated lines out of a pasted list. Paste your list with one item per line and click Run; the cleaned list appears in the output box, in the same order as your original list minus the repeats.
Which copy of a repeated line does it keep?
The first one. The tool reads your list top to bottom and keeps the earliest occurrence of each exact line, dropping every later repeat.
Does it treat "Apple" and "apple" as the same line?
No. The comparison is case-sensitive, so different capitalization counts as a different line. Convert the list to one case first if you want those variants treated as duplicates.
Is my text uploaded or saved anywhere?
No. De-duplication runs entirely in your browser using plain JavaScript. Nothing you type or paste is uploaded or sent to a server, and nothing is saved - refreshing or leaving the page clears the box.
Is there a limit to how much text I can paste in?
No. The input box has no built-in length limit, and Remove Duplicate Lines reprocesses whatever text is currently in the box every time you click Run, whether that is 8 lines or 8,000.
Is there a one-click Copy button?
No. Select the text in the output box yourself (Ctrl+A then Ctrl+C, or Cmd+A then Cmd+C on a Mac) and paste it wherever you need it.
Does it tell me how many duplicate lines it removed?
No. Remove Duplicate Lines shows only the cleaned list, not a count of what was removed. Compare the number of lines before and after, or run the list through the word counter tool first if you want a line count.