Remove Duplicate Lines
Delete repeated lines from a list and keep the original order.
How to use Remove Duplicate Lines
- Paste your list, one item per line (or open a .txt or .csv file).
- Choose whether case and spaces should count as differences.
- Copy the cleaned list. The status line shows how many duplicates were removed.
How it works
Each line is compared with every line before it. When two lines match under your rules, only one is kept, either the first or the last occurrence, and the original order of the remaining lines is preserved. Nothing is sorted unless you sort afterwards with Sort Lines.
With Ignore upper/lower case, "Apple" and "apple" are treated as the same item, and the copy that is kept keeps its original spelling. With Ignore leading/trailing spaces, stray spaces from copy-paste no longer hide duplicates.
Example
The list *apple, banana, Apple, cherry, banana* with "ignore case" on becomes *apple, banana, cherry*: 2 duplicates removed.
Frequently asked questions
Does it change the order of my lines?
No. Lines stay in their original order; only repeats are removed. To sort as well, run the result through Sort Lines.
Can I remove duplicates from a CSV column?
Yes, if each value is on its own line. For a whole CSV row to count as a duplicate, the entire line must match.
How large a list can it handle?
Hundreds of thousands of lines work on a typical laptop because the comparison uses a hash set rather than comparing every pair.
Is my list uploaded?
No. Processing happens in this page and nothing is stored.
Limitations
- Lines must match exactly (apart from the case and space options); near-duplicates such as typos are not detected.
- Comparison is per line; duplicate words inside a line are not removed.
Last reviewed November 9, 2026. How we build and test tools.