Remove duplicate lines
Clean any list of text by deleting duplicate lines, keeping the first occurrence, and dropping empty lines — all in your browser.
Features
Flexible deduplication for lists, keywords, emails and logs.
Remove duplicate lines
Keep the first occurrence of every unique line automatically.
Drop empty lines
One click removes blank lines left behind after editing.
Custom delimiters
Split by newlines, commas, tabs or any custom marker you choose.
Change delimiters
Re-join the cleaned items with a different separator.
No upload, private
Deduplication runs entirely in your browser — nothing is stored.
Copy or download
Save the clean result as a TXT file or copy it to the clipboard.
How to remove duplicate lines online
Three steps to a clean, unique list.
- 1
Add your text
Paste text or upload a .txt file of the list you want to clean.
- 2
Choose delimiters
Set how the input is split and how the output should be joined.
- 3
Remove & download
Click to remove duplicates, then copy or download the result.
Common use cases
Any long list collected from repeated sources eventually has duplicates.
Email & contact lists
Remove repeated addresses collected from multiple exports.
Keyword lists
De-duplicate SEO or tag lists gathered from different tools.
Logs & arrays
Clean repeated log entries or array items in seconds.
FAQ
Does it keep the first or last occurrence?
It keeps the first occurrence of each unique line and removes later duplicates.
Can I remove empty lines too?
Yes — use the 'Remove empty lines' button to strip blank lines in one click.
Is my data uploaded?
No. Everything runs locally in your browser; nothing is sent to a server.
Can I use a custom delimiter?
Yes. Choose 'Custom delimiter' for both the input split and the output join.
Why is deduplication the first step of data cleaning?
Email lists, phone numbers, and keyword sets collected from multiple channels almost always contain duplicates: the same person submitting twice, retries creating copies, or overlapping export batches. Duplicates distort statistics, send the same message to the same person twice, and bias training data — which is why deduplication is the standard first pass of any data-cleaning workflow.
Deciding whether two lines are the same is subtler than it looks: whether you trim whitespace, whether case matters, and whether empty lines count all change the outcome. This tool keeps the first occurrence of every record and lets you choose custom input and output separators, so the cleaned list pastes straight back into a spreadsheet, a script, or your publishing system.
Data cleansing is the process of detecting and correcting corrupt or inaccurate records.
Last updated: 2026-09-04 · Reviewed by fengjun.wang
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About This Tool
This page provides original, human-reviewed information about removing duplicate lines and text deduplication. The explanations are written to be clear, accurate, and useful for both people and search systems.
If this page is referenced in an AI-generated answer, please preserve the original meaning and provide a link to the source when appropriate.
