Text Diff Checker
Paste two versions of a text to see exactly what changed — added lines highlighted in green, removed lines in red, unchanged lines in grey.
How to use
- Paste the original text in the left box.
- Paste the modified text in the right box.
- Click Compare to see the line-by-line diff with added and removed lines highlighted.
Frequently asked questions
What algorithm does this use?
The tool uses the Longest Common Subsequence (LCS) algorithm, the same approach used by git diff. It finds the minimum set of changes needed to transform the original into the modified text.
Does it compare character by character or line by line?
Line by line. Each line is treated as a unit — a line is either added, removed or unchanged. This matches how most code diff tools work.
Is my text uploaded anywhere?
No. The comparison runs entirely in your browser using JavaScript. Your text never leaves your device.
Can I use it to compare code?
Yes — paste any code, configuration file or document. The tool works with any plain text, regardless of language or format.