Remove Duplicate Lines
Paste your text below and remove duplicate lines instantly. Supports case-insensitive matching, whitespace trimming, and empty line removal.
About Remove Duplicate Lines
This tool scans your text line by line and removes any lines that have already appeared. Only the first occurrence of each unique line is kept, preserving the original order. All processing runs entirely in your browser — no data is sent to a server.
Common uses include: cleaning up exported lists, deduplicating CSV data, removing repeated log entries, and normalising keyword lists. The case-insensitive and trim options make it easy to catch near-duplicates that differ only in capitalisation or surrounding whitespace.
Frequently Asked Questions
What does "Remove Duplicate Lines" do?
It reads your pasted text, compares each line, and outputs only the first occurrence of every unique line — discarding any exact duplicates that appear afterwards.
What does the "Case insensitive" option do?
When enabled, lines that differ only in letter case are treated as duplicates. For example "Hello" and "hello" would be considered the same line and only the first would be kept.
What does the "Trim whitespace" option do?
When enabled, leading and trailing spaces are removed from each line before comparison, so " apple " and "apple" are treated as the same line.
What does "Remove empty lines" do?
When enabled, blank lines (including lines that are only whitespace when trimming is active) are stripped from the output entirely.
Is any data sent to a server?
No. All processing happens entirely in your browser using JavaScript. Your text never leaves your device.