Duplicate Lines Remover
Strip repeated lines from any list — with case-insensitive and trim options — and see what was removed.
About This Tool & Technical Logic
The tool splits input into lines, optionally trims each line and folds case, then keeps only the first occurrence of every distinct line — preserving the original order unless sorting is requested.
Typical uses: cleaning exported keyword lists, de-duplicating URL rosters, and merging log extracts. The comparison key is the (optionally normalized) line text, so " Apple " and "apple" can be treated as the same entry.
Keep first occurrence per normalized key: seen.has(key) ? skip : keep — O(n) with a Set.
How to Use — Step by Step
- 1
Paste your list
One entry per line. Blank lines are dropped automatically since they rarely carry meaning.
- 2
Choose normalization
Trim handles copy-paste spacing noise; case-insensitive matching treats URL paths and names as duplicates regardless of capitalization.
- 3
Review the stats and copy
The tool reports lines in, unique out, and duplicates removed so you can sanity-check before replacing your data.
Frequently Asked Questions
No — the first occurrence of each line keeps its original position. Enable sorting only if you want an alphabetized result.