Free online text diff checker and comparison tool. Compare two texts and see differences instantly with color-coded additions, deletions, and unchanged lines. Perfect for comparing code, documents, and prose. Privacy-first: all processing happens in your browser.
Paste the original text in the left box and the modified text in the right box. Or use the sample button to see how diff works with example text.
Click Compare Texts to see the differences between the two versions. Added lines appear in green, removed lines in red, and unchanged lines remain neutral.
Scroll through the diff output to review every change. Use the Swap button to reverse which text is considered original vs modified.
Q: Is my text uploaded to a server?
A: No — all text comparison happens entirely in your browser. Your text never leaves your device.
Q: How does the diff algorithm work?
A: It uses a line-by-line comparison with LCS (Longest Common Subsequence) algorithm to identify added, removed, and unchanged lines.
Q: Can I compare large files?
A: The tool handles texts with hundreds of lines efficiently. For very large files, it may take a moment to process but works entirely client-side.