This diff checker compares two versions of a text and shows exactly which lines were added, removed or left unchanged. It is line-based, runs entirely in your browser, and can ignore case or extra whitespace when that noise is not relevant.
Your data is processed locally in your browser and is not uploaded to our server.
Paste both versions to compare them The line-by-line differences appear here as soon as both sides contain text.
These texts are too large to compare safely. Reduce each side to 800 lines or 100,000 characters.
Longest common subsequence of the two line arrays
The tool finds the longest sequence of lines that appears in both texts. Everything outside that sequence is reported as removed from the original or added in the modified version.
Key = line, optionally lowercased and whitespace-normalised
With either ignore option enabled, lines are compared by their normalised key but displayed exactly as written. A line that differs only in case or spacing is then treated as unchanged.
The second line of a three-line text was edited.
The diff shows the old line with a minus and the new line with a plus. The surrounding lines stay visible as context.
A file was reformatted with different indentation.
The diff becomes empty aside from unchanged lines, which is useful when reviewing formatting-only commits.
A one-word edit inside a line is shown as one removed line and one added line, not as a word-level highlight. This keeps the result easy to read and copy.
Very large inputs are refused rather than freezing the page. The limit is 800 lines or 100,000 characters per side; split the text into smaller sections for a larger comparison.
Windows and Unix line endings are normalised before comparing, so a file does not appear completely different just because it uses CRLF instead of LF.
No. The comparison is line-based: a modified line appears once as removed and once as added. That is usually clearer for code, lists and documents.
Green lines with a plus were added in the modified text; red lines with a minus were removed from the original; grey lines are unchanged. Each line also has a screen-reader label, so the meaning does not depend on colour alone.
It trims leading and trailing spaces and collapses repeated spaces before comparing. Indentation-only changes then count as unchanged.
Comparing very large texts line by line would make the page unresponsive. The tool limits each side to 800 lines or 100,000 characters; compare smaller sections instead.
No. The comparison runs locally in your browser and the text is not sent anywhere.