Remove Duplicate Lines Online
This free deduplication tool deletes repeated lines from any text or list in one click. Paste email lists, keyword lists, log files, or CSV fragments and get back only unique lines — no spreadsheet formulas or command-line tools required.
Matching can be tuned to your data: ignore letter case, ignore whitespace differences, trim lines before comparing, and drop empty lines. You can also choose whether the first or the last occurrence of each duplicate is kept. Everything runs client-side in your browser.
How to use Remove Duplicates
- Paste your text into the Input box (one entry per line).
- Pick matching options: Ignore case treats "Apple" and "apple" as duplicates; Ignore whitespace differences collapses runs of spaces before comparing.
- Optionally enable Trim whitespace or Remove empty lines to clean the list at the same time.
- Leave "Keep first occurrence" checked to keep the first copy of each duplicate, or uncheck it to keep the last.
- Press Process, then copy or download the deduplicated list.
Related terminology
- Deduplication
- The process of removing repeated entries from a data set so each value appears only once.
- Case-insensitive matching
- Comparing text without distinguishing uppercase from lowercase, so "John" and "john" count as the same value.
- Unique lines
- The set of lines that remain after duplicates are removed — equivalent to the output of the Unix command "sort -u", but without changing line order.
Frequently asked questions
- How do I remove duplicate lines from a list online?
- Paste the list into the input box and press Process. Every repeated line is removed and the unique lines are returned in their original order.
- Does the order of my list change?
- No. Unlike spreadsheet deduplication that often requires sorting first, this tool preserves the original order of the surviving lines.
- Can I treat lines that differ only in capitalization as duplicates?
- Yes — enable the Ignore case option and "Apple", "APPLE", and "apple" will be collapsed into a single line.
- What does "Keep first occurrence" do?
- When a line appears multiple times, the tool keeps the earliest copy by default. Unchecking the option keeps the final copy instead, which matters when later entries are more up to date.