How to Remove Duplicate Lines
Merged exports, pasted lists and scraped data all end up with the same entry appearing several times. Paste your list and the repeats disappear immediately — but what makes deduplication trustworthy is seeing what happened, which is where most tools stop short. Alongside the clean result you get a stats row showing total lines, how many unique ones survived and the percentage reduction, a frequency breakdown of the most-repeated entries, and a panel that reveals the exact lines that were dropped. Nothing vanishes silently. Two matching options handle the cases that catch people out. Ignore case treats Apple and apple as the same entry, and ignore spacing collapses differences in leading, trailing and repeated whitespace — the reason two lines that look identical often fail to deduplicate elsewhere. You also choose whether the first or the last occurrence is the one that survives, which matters when later entries carry newer information. Optional trimming, blank-line removal and alphabetical sorting finish the cleanup in the same pass. Everything runs in your browser.
Paste your list
One item per line; duplicates are found instantly.
Set the matching
Choose keep first or last, and how strictly to compare.
Review & copy
Check the removed lines, then copy the clean list.
Keep First vs Keep Last
Keep first
The earliest occurrence survives and later repeats are dropped. This preserves the original ordering of the list, which is usually what you want for a straightforward cleanup.
Keep last
The final occurrence survives instead. Useful when a list is append-only and later entries supersede earlier ones — an updated record or a corrected value further down the file.
Common Use Cases
Clean an email list
Remove repeated addresses before importing into a mailing tool.
Deduplicate keywords
Strip repeats from a keyword list gathered across several sources.
Merge two lists
Paste both together and remove the overlap in one pass.
Tidy log output
Collapse repeated log lines to see the distinct messages.
Clean scraped data
Remove duplicate rows pulled from multiple pages.
Unique URLs
Reduce a crawl list to distinct addresses before processing.
Product SKUs
Ensure each identifier appears only once in an import.
Find repeats
Use the frequency panel to see which entries repeat most.
Tips & Best Practices
Leave ignore spacing on
Invisible trailing spaces are the most common reason identical-looking lines survive deduplication.
Check the removed panel
Before using the result, glance at what was dropped — especially with ignore case turned on.
Keep last for append-only data
When later entries supersede earlier ones, keeping the last occurrence preserves the newest value.
Watch the reduction figure
An unexpectedly high percentage usually means your matching is looser than intended.
Deduplicate before sorting elsewhere
A smaller list is faster to work with and easier to review.
Mind case for identifiers
Turn off ignore case when codes or IDs are genuinely case-sensitive.
Troubleshooting
Identical lines weren't removed
One probably has trailing whitespace or different capitalisation. Turn on ignore spacing and ignore case.
Too many lines were removed
Ignore case may be merging entries that should stay separate. Open the removed panel to check, then turn it off.
The order changed
Sort result is on. Turn it off to keep the original ordering of the surviving lines.
Blank lines disappeared
Remove blank lines is on by default. Turn it off if empty lines are meaningful in your list.
Frequently Asked Questions
How do I remove duplicate lines for free?
Paste your list with one item per line and the repeats are removed instantly. Copy the clean result — free, no signup.
Does it keep the first or last occurrence?
Either. Choose keep first to preserve original order, or keep last when later entries supersede earlier ones.
Can it ignore capitalisation?
Yes. With ignore case on, Apple and apple are treated as the same line.
What does ignore spacing do?
It matches lines that differ only by leading, trailing or repeated whitespace — the usual cause of missed duplicates.
Can I see what was removed?
Yes. The show-removed panel lists every dropped line, so nothing disappears silently.
Does it count how often lines repeat?
Yes. A frequency panel shows the most-repeated entries with their counts.
Does it change the order?
No, unless you turn on sort result. Otherwise the surviving lines stay in their original order.
Are blank lines removed?
By default yes. Turn off remove blank lines if empty lines matter in your list.
Does it trim whitespace?
Trimming is optional and separate from ignore spacing — trim rewrites the lines, ignore spacing only affects matching.
Can I sort the result?
Yes. Turn on sort result for alphabetical order with natural number handling.
Is my list sent to a server?
No. Everything runs in your browser, so your data never leaves your device.
How many lines can it handle?
It comfortably processes thousands of lines right in your browser.
Can I download the result?
Yes. Save the unique lines as a .txt file, or copy them to your clipboard.
Does it work with email lists?
Yes. Put one address per line, and turn on ignore case since email addresses are case-insensitive in practice.
What is the reduction percentage?
The share of your original lines that were duplicates and got removed.
Does it work offline?
Once the page has loaded it runs entirely in your browser, so it keeps working without a connection.
Does it work on phones?
Yes, in any modern browser on Windows, Mac, Android or iPhone with nothing to install.
Is this tool really free?
Completely free, forever — no account, no ads and no premium wall.
100% free · No signup · Processed in your browser · Data never sent
Last updated: August 2026 · FlipMyFormat Remove Duplicate Lines
Written and maintained by the FlipMyFormat team · Runs entirely in your browser