Find Duplicate Lines
Find and list every line that appears more than once, with its exact occurrence count. Optional case-insensitive matching. Runs 100% in your browser.
What is the Find Duplicate Lines?
Find Duplicate Lines scans your text and lists every line that appears more than once, showing exactly how many times each one occurs.
- Lists only the lines that repeat
- Shows the exact count for each duplicate
- Optional case-insensitive comparison
- Handy summary of how many duplicates were found
- Client-side only — nothing is uploaded
How to use the Find Duplicate Lines
- 1
Paste your text into the input box, one item per line.
- 2
Optionally enable case-insensitive matching.
- 3
Review the list of duplicate lines and their occurrence counts.
- 4
Copy or download the duplicates report.
About the Find Duplicate Lines
Find Duplicate Lines scans your text and lists every line that appears more than once, showing exactly how many times each one occurs. Paste a list, log or export and immediately see which entries are repeated and how often.
It is useful for auditing data, catching duplicate records, cleaning mailing lists, or finding repeated log messages. Turn on case-insensitive matching so that lines differing only in capitalization are treated as the same value.
All the analysis runs locally in your browser, so your data is never uploaded. That keeps sensitive lists private and lets you find duplicates even without an internet connection.
Frequently asked questions
How do I find duplicate lines in a list?
Paste your list and the tool instantly lists any line that appears more than once, along with how many times it occurs.
Can it ignore capitalization?
Yes. Enable case-insensitive matching and lines that differ only in upper or lower case are counted as the same line.
Does it change my original text?
No. It only reports the duplicates it finds. To remove them, use a remove-duplicate-lines tool instead.
Is my data uploaded?
No. The comparison runs entirely in your browser, so your text stays on your device and works offline.
Guides for Find Duplicate Lines
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