Paste two versions of a text to see exactly what changed, line by line and word by word. Switch tabs to clean a list by removing duplicate lines, keeping only unique ones, or listing just the repeats.
A diff shows the smallest set of changes that turns one text into another. This tool finds the longest run of lines the two versions share, marks every other line as removed (red) or added (green), and then highlights the individual words that changed inside lines that were edited. It is useful for comparing drafts of a document, configuration files, copied code, contract revisions and exported lists.
| Mode | Result |
|---|---|
| Remove duplicates (keep first) | Every distinct line once, in original order |
| Keep only lines that appear once | Drops every line that is repeated anywhere |
| Show only the repeated lines | One copy of each line that occurs more than once |
You can also trim spaces, ignore case, drop empty lines and sort the output alphabetically with natural number ordering. All processing happens in your browser, so confidential text is never uploaded.
Is my text sent to a server? No. Both the comparison and the duplicate removal run locally in your browser, and nothing is stored or uploaded.
How does the tool decide what changed? It looks for the longest sequence of lines that appear in both texts in the same order. Lines outside that sequence are marked as added or removed.
Why are some words highlighted inside a line? When a removed line sits next to an added line, the tool compares them word by word and highlights only the parts that differ, so small edits are easy to spot.
Can I remove duplicates but ignore capital letters? Yes. Turn on Ignore case and lines such as Apple and apple count as the same, with the first one kept.
Is there a size limit? There is no fixed limit, but extremely large inputs, such as tens of thousands of different lines on each side, may be refused to keep your browser responsive.