Remove Duplicate Lines — Free Online Deduplicator
Paste a list, get it back with every repeat removed — order preserved.
🔒 Runs in your browser — files never uploaded ⚡ No signup 💯 Free
Paste any list — emails, URLs, keywords, product codes, log lines — and get it back with the duplicates removed. The first occurrence of each line is kept and the original order is preserved, so the list you get out is recognisably the list you put in, minus the repeats.
Everything runs in your browser. Lists are exactly the kind of data that shouldn't be pasted into a random server — email lists especially — and here they never leave your machine.
How to use Remove Duplicate Lines
- Paste your list, one item per line.
- Pick your options. Ignore case treats Apple and apple as the same line; trimming ignores stray spaces at the ends.
- Click Remove duplicates and check the counts — how many lines survived, how many repeats went.
- Copy the result or download it as a .txt file.
What counts as a duplicate?
By default, lines must match exactly. The options loosen that in the two ways that cover almost every real list:
- Ignore case —
john@example.comandJohn@Example.combecome one entry. For email lists you almost always want this on. - Ignore surrounding spaces — a line with an invisible trailing space is the same line. This one is on by default because those spaces are nearly always paste artefacts, and a "duplicate" that survives deduplication because of one is maddening to debug.
Whichever spelling appears first is the one that survives — the options change how lines are compared, never how they're written out.
Why order is preserved
Most deduplicators sort the output, which destroys any meaning the order carried — a ranked keyword list, a priority order, steps that repeat. Keeping first-occurrence order loses nothing: if you want it sorted, tick the sort option, or use the line sorter for full control over the ordering.
Common uses
- Email lists — merge exports from two systems, dedupe case-insensitively, and the double-sends stop.
- Keyword research — combine suggestions from several tools into one clean list.
- Log files — collapse repeated error lines to see the distinct failures.
- Spreadsheet columns — paste a column straight in; each cell arrives as a line.
Frequently asked questions
Which copy of a duplicate is kept?
The first one, in its original spelling and position. The options change how lines are compared — case, surrounding spaces — never what is written out, so with "ignore case" on, whichever capitalisation appeared first is what survives.
Is my list uploaded anywhere?
No. The deduplication runs entirely in your browser — nothing is sent over the network. That matters for the lists people actually dedupe: email addresses, customer records, keyword research you'd rather competitors didn't see.
Does it keep the original order?
Yes, by default — each line stays where it first appeared, which most tools needlessly destroy by sorting. If you want it sorted, tick "Sort the result A→Z", or use the line sorter afterwards for more orderings.
Why didn't two lines I consider duplicates get merged?
They differ in some way the current options preserve — usually case (turn on "ignore case") or an invisible character. Trailing spaces are handled by the trim option; a tab or a non-breaking space in one copy will still keep them distinct, and the find & replace tool can normalise those first.
How big a list can it handle?
Hundreds of thousands of lines are fine — the work is a single pass with a hash set, and it happens on your machine. The practical limit is your browser's memory, which for text lists is far beyond anything you'd paste.
Can I dedupe a spreadsheet column?
Yes — copy the column in Excel or Google Sheets and paste it here; cells arrive one per line. Dedupe, copy the result, and paste it back. (Sheets also has =UNIQUE() if you want it live in the spreadsheet.)