Duplicate Line Remover
Remove duplicate lines from a list or block of text, or isolate just the duplicates, with options for case sensitivity, whitespace trimming, blank lines, and sorting — instantly, entirely inside your browser.
What is a duplicate line remover?
A duplicate line remover scans a list — one item per line — and strips out any line that repeats, leaving only the first occurrence of each unique value behind. It's the fastest way to clean up an email list, a spreadsheet column pasted as text, a set of URLs, a keyword list, or any other line-based data where repeats have crept in from merging files, exporting reports, or copy-pasting from multiple sources.
Beyond simply removing duplicates, it can also flip the logic and show only the lines that repeat, which is useful when the goal is to find and review the duplicates themselves rather than discard them — for example, auditing a list for accidental double entries before deciding how to handle them.
GuideHow to use it
How the comparison works
Each line is compared against every other line to find matches. With "Case sensitive" on, "Apple" and "apple" are treated as different lines; turn it off to match them regardless of letter case. "Trim whitespace" strips leading and trailing spaces from every line before comparing, which catches duplicates that only differ by accidental spacing. "Remove blank lines" drops empty lines from the result entirely, and "Sort alphabetically" orders the final output from A to Z once duplicates have been handled. The "Total lines," "Unique," and "Duplicates" counters update live as the input or options change.
Why it helpsFeatures & benefits
Why this runs entirely in your browser
Lists pasted here often contain emails, customer data, or other sensitive information, so nothing is ever uploaded. Every comparison and filter runs in JavaScript locally in the tab, which means it keeps working offline once the page has loaded and nothing typed or uploaded here persists after the tab is closed.
Common uses
Deduplicating an email or contact list before a mail merge, cleaning up a keyword list exported from a research tool, removing repeated URLs from a crawl or sitemap, tidying a list of usernames or IDs, or checking a spreadsheet column that was pasted as plain text for accidental repeats before importing it elsewhere.
Frequently asked questions
A few things people usually want to know before trusting the numbers.
It removes every repeated line after its first occurrence, keeping just one copy of each unique line in its original order.
It flips the logic and returns only the lines that appear more than once, which is useful for reviewing exactly what's repeated before deciding what to do about it.
Yes. With case sensitivity on, "Apple" and "apple" count as different lines; turn it off to treat them as the same duplicate.
Yes. Use the Upload .txt button to load a plain text file directly into the input box.
No. All comparisons happen locally in your browser. Nothing typed or uploaded here is sent to a server, stored, or shared.