How does it decide two lines are duplicates?

Exact match after your chosen normalization: with “trim whitespace” on, “ apple ” and “apple” count as the same line; with “ignore case” on, “Apple” and “apple” do too. The first occurrence is always the one kept.

Does it keep my original order?

Yes — by default lines stay in their original order, minus the duplicates. If you want an alphabetical result instead, switch on “Sort A–Z” and the deduplicated list is sorted for you.

Is my list uploaded anywhere?

No. Deduplication happens entirely in your browser — email lists, customer exports and keyword sets never leave your device, nothing is stored, and the tool works offline once the page has loaded.

How large a list can it handle?

Tens of thousands of lines are processed instantly — the tool uses a hash set, so each line is checked in constant time. Practical limits come from your device’s memory, not from the tool, and there’s no artificial cap.

Can it remove empty lines too?

Yes — tick “Remove empty lines” and blank lines disappear along with the duplicates. Without it, the first empty line is kept (further empty lines are duplicates of it, so they’re removed anyway).

What do people use this for?

Cleaning email and mailing lists, deduplicating SEO keyword sets, merging exports from several systems, tidying log output, comparing inventory lists, and prepping data before import — anywhere “paste, dedupe, copy back” beats writing a script.

Does it tell me how many duplicates were found?

Yes — the stats above the result show lines in, lines kept and lines removed, updating live as you toggle options. If “removed” is zero, your list was already clean.

Remove Duplicate Lines

Paste a list and get it deduplicated in one click — trim, ignore-case and sort options, nothing uploaded.

Files never leave your device Instant — no upload waitFree, no sign-up

Paste your lines

Trim whitespace firstIgnore caseRemove empty linesSort A–Z

Remove duplicate lines from any list — in one paste

Merged two exports? Copied a keyword list twice? Paste it above and this tooldeduplicates instantly, keeping the first occurrence of every line and telling you exactly how many were removed. Original order is preserved — or flip on Sort A–Zfor an alphabetical result.

Normalization options that catch “almost duplicates”

Real lists rarely duplicate cleanly — one entry has a trailing space, another differs only in capitalization. Trim whitespace and ignore case catch those near-misses, and remove empty lines clears the blanks while you’re at it. Live counters show lines in, kept and removed, so nothing disappears silently.

Built for the lists you can’t paste just anywhere

Deduplication jobs are usually people data: email lists, customer names, order IDs. This tool runs entirely in your browser — nothing is uploaded, logged or stored, and it keeps working offline once loaded. Tens of thousands of lines dedupe in a blink, because it’s your own device doing constant-time set lookups.

A tidy step in a bigger cleanup

Dedupe pairs naturally with the rest of the text toolbox: normalize capitalization first with thecase converter, compare the cleaned list against another version in the diff checker, or convert the final list to JSON withTXT to JSON for your code.

Frequently Asked Questions

How does it decide two lines are duplicates?
Exact match after your chosen normalization: with “trim whitespace” on, “ apple ” and “apple” count as the same line; with “ignore case” on, “Apple” and “apple” do too. The first occurrence is always the one kept.
Does it keep my original order?
Yes — by default lines stay in their original order, minus the duplicates. If you want an alphabetical result instead, switch on “Sort A–Z” and the deduplicated list is sorted for you.
Is my list uploaded anywhere?
No. Deduplication happens entirely in your browser — email lists, customer exports and keyword sets never leave your device, nothing is stored, and the tool works offline once the page has loaded.
How large a list can it handle?
Tens of thousands of lines are processed instantly — the tool uses a hash set, so each line is checked in constant time. Practical limits come from your device’s memory, not from the tool, and there’s no artificial cap.
Can it remove empty lines too?
Yes — tick “Remove empty lines” and blank lines disappear along with the duplicates. Without it, the first empty line is kept (further empty lines are duplicates of it, so they’re removed anyway).
What do people use this for?
Cleaning email and mailing lists, deduplicating SEO keyword sets, merging exports from several systems, tidying log output, comparing inventory lists, and prepping data before import — anywhere “paste, dedupe, copy back” beats writing a script.
Does it tell me how many duplicates were found?
Yes — the stats above the result show lines in, lines kept and lines removed, updating live as you toggle options. If “removed” is zero, your list was already clean.