Duplicate Line Remover
Strip duplicate lines from any list — case-sensitive or insensitive, preserving order or sorted.
Last updated: April 2026 · Runs in your browser · No sign-up
When you need this
Cleaning up email lists before import, deduping log lines, merging CSV exports from multiple sources, or just tidying a hand-typed list — removing duplicates is a one-click task that would otherwise need a spreadsheet or a shell script.
Shell equivalent
Power users often reach for sort -u file.txt or awk '!seen[$0]++'. This tool gives you the same result without opening a terminal, and with a visual diff of what was removed.
Frequently Asked Questions
Does it preserve the original order?
Yes by default. The first occurrence of each line is kept; subsequent duplicates are dropped. You can also choose to sort the result.
Is the comparison case-sensitive?
You decide. Case-sensitive treats 'Apple' and 'apple' as distinct; case-insensitive merges them (keeping the first-seen casing).
What about whitespace differences?
Trailing spaces and tabs can silently prevent deduplication. Use the 'trim whitespace' option to normalise each line before comparing.
How large a list can it handle?
Tens of thousands of lines are fine. The tool uses a hash Set, so performance is O(n) regardless of order.