Duplicate Line Remover

What the duplicate Line Remover does

This tool treats your text as a list of lines and keeps only the first appearance of each one. It is the fastest way to clean an email list pulled from two overlapping exports, collapse a log file down to its distinct messages, or check whether a keyword list has drifted out of shape.

Five options change what counts as a duplicate. Ignore letter case treats Alpha@example.com and alpha@example.com as the same entry — usually what you want for email addresses and domain names, rarely what you want for passwords or case-sensitive identifiers. Trim spaces strips leading and trailing whitespace before comparing, which catches the very common case of an item that only looks unique because it carries a stray tab from a copy-paste. Drop blank lines removes empty rows entirely. Sort reorders the output alphabetically using natural numeric ordering, so item2 comes before item10.

The fifth option inverts the whole job. Show only the duplicated items gives you the entries that appeared more than once, rather than the deduplicated list — useful when the repeats are the thing you are investigating, such as finding which order IDs got processed twice. The counters underneath tell you how many lines went in, how many came out, and how many were removed, so you have a quick sanity check on whether the result is plausible before you use it.

How to use it

1. Paste your list into the left-hand box, one item per line.
2. Set the matching options. Leaving case-insensitive and trim-whitespace on suits most real-world lists.
3. Read the counters to confirm the result looks right, then copy it or download it as a .txt file.

A worked example

A subscriber export merged from two sources:

alpha@example.com
beta@example.com
alpha@example.com
Gamma@example.com
gamma@example.com
beta@example.com

With ignore letter case on, six lines in becomes three lines out and three removed:

alpha@example.com
beta@example.com
Gamma@example.com

Note that the first spelling wins — Gamma@example.com survives and the later lowercase version is dropped. Turn ignore letter case off and you get four lines instead, because the two spellings of gamma are then treated as different people. Which behaviour is correct depends on your system; email addresses are case-insensitive in practice, so the default is usually right.

Frequently asked questions