Remove Duplicate Lines
Delete repeated lines from any list and see exactly how many were removed. Free, instant and private — your list is processed in your browser and never uploaded.
How to remove duplicate lines
- Paste your list. Put one item per line in the box above — emails, URLs, keywords, names or any other list.
- Choose your options. Pick a mode and decide whether comparison should ignore case, trim whitespace and drop blank lines.
- Copy the clean list. The de-duplicated result and a count of removed lines appear instantly, ready to copy or download.
About this tool
This free tool removes duplicate lines from a list while preserving the original order of the first time each line appears. It is perfect for cleaning up email lists, deduplicating URLs and keywords, tidying CSV columns, merging two lists, or preparing data before importing it somewhere that rejects duplicates. Beyond the standard “keep first occurrence” mode, you can also keep only the lines that appear exactly once, or extract just the lines that were duplicated.
Comparison options let you handle real-world messiness: ignore letter case, trim leading and trailing spaces so " apple " matches "apple", and strip out blank lines. Everything runs locally in your browser, so even large lists are processed instantly and your data never leaves your device — safe for private contact lists and confidential records.
Frequently asked questions
Does it keep the original order of my list?
Yes. In the default mode the first occurrence of each line stays exactly where it was, and later duplicates are removed. The tool does not sort your list — if you also want it sorted, run the result through our Sort List tool.
What is the difference between the three modes?
“Remove duplicates” keeps one copy of every line. “Keep only lines that appear once” removes every line that has any duplicate, leaving genuinely unique items. “Keep only the duplicated lines” does the opposite, showing you which lines were repeated.
How does the case-insensitive option work?
When enabled, lines are compared without regard to letter case, so “Apple” and “apple” are treated as duplicates. The line that is kept in the output keeps its original casing exactly as you typed it.
Is there a limit on list size?
There is no fixed limit. The de-duplication uses an efficient hash set and runs entirely in your browser, so it comfortably handles lists with hundreds of thousands of lines.