Paste text, remove duplicates.
Every option updates the output live — no button to press, no page reload.
Nothing is uploaded or stored — everything happens on your device.
Clean lines in four steps.
No manual needed — here's the entire flow.
Paste your text
Drop in any list, log file, or block of text — each new line is treated as one entry.
Choose options
Toggle case sensitivity, whitespace trimming, empty-line removal, and whether to keep the first or last occurrence.
See the clean output
Duplicates vanish instantly. The result updates live as you type or change any option.
Copy and use
Hit the copy button and paste the deduplicated text wherever you need it.
Clean text, your way.
Every option is designed to give you exactly the output you need.
Duplicate removal
Every repeated line is collapsed into a single instance — no matter how many times it appeared.
Flexible matching
Control whether "Hello" and "hello" are treated as the same line, and whether spaces around lines are ignored.
Advanced control
Choose which occurrence to keep, and optionally strip out blank lines for a fully polished result.
Questions people actually ask.
The short answers — with the long ones one tap away.
How does the remove duplicate lines tool work?+
Paste your text into the input box and the tool will instantly identify and remove duplicate lines. You can choose to keep the first or last occurrence, enable case-sensitive matching, trim whitespace, and remove empty lines.
Is the duplicate removal case-sensitive?+
By default, the tool treats lines as duplicates regardless of case (e.g., 'Hello' and 'hello' are considered the same). You can enable the "Case-sensitive" option to treat them as distinct.
Can I remove empty lines as well?+
Yes. There is a dedicated "Remove empty lines" option. When enabled, any blank lines or lines containing only whitespace will be removed from the output.
Does it keep the first or the last occurrence of a duplicate line?+
You can choose. By default, the tool keeps the first occurrence of each unique line. Toggle the "Keep last occurrence" option if you prefer to retain the last instance instead.
Is my text stored or sent anywhere?+
No. Everything is processed locally in your browser. Your text is never uploaded, logged, or stored by StudyWithSTEM.
Is there a limit to how much text I can paste?+
No hard limit — the tool runs entirely in your browser, so very long texts may simply take a moment longer to process on older devices.