About This Tool
Remove Duplicate Lines helps organize URLs, identifiers, and names. It separates comparison keys from output: even when you ignore case or trim for comparison, it keeps the first original line.
How to Use It
- Enter one item per line.
- Choose case sensitivity, whether to trim before comparison, and whether to keep blank lines.
- Click Remove Duplicates and review the original, resulting, and removed line counts.
- Copy or download the TXT output. Original order is preserved by default.
Examples
- apple, banana, apple, orange, banana → apple, banana, orange, in order of first appearance.
- With case sensitivity off, Apple, apple, and APPLE keep only the first Apple.
- With comparison trimming on, apple and apple surrounded by spaces can match, but the first original line is not trimmed in the output.
Rules and Limits
Line breaks are normalized to LF before comparison. Case sensitivity and original order are on by default; comparison trimming is off. When blank lines are kept, only the first matching blank line remains. Turning that option off removes whitespace-only lines. A set tracks comparison keys without sorting away the order of first appearance.
Common Uses
- Clean up duplicate URLs and filenames.
- Remove repeated entries after merging lists.
- Compare case-insensitively without rewriting the retained text.
Privacy
Text processing, file reading, conversion, and previews all run locally in this browser. Input is not uploaded or automatically saved. No backend, database, online API, or third-party CDN is used. Copying and downloading also happen locally.
FAQ
Which occurrence is kept?
The first original line is always kept. By default, retained lines appear in their original order.
Do different letter cases count as duplicates?
Not by default. Turn case sensitivity off to lowercase comparison keys while preserving the first line’s original case.
Do leading and trailing spaces matter?
By default, yes. Trim before comparison changes only comparison keys and does not silently trim the output.
How are blank lines handled?
If blank lines are kept, only the first matching blank line remains. If the option is off, whitespace-only lines are removed. The current rule is shown in the controls.