Text Diff Checker
Paste two versions of a text and see which lines were added, removed, or unchanged.
How to use the text diff checker
- Paste the original text in the left field, and the new version in the right field.
- Press "Compare".
- Unchanged lines are shown normally, removed lines are marked red, and new/changed lines are marked green.
How does the comparison work?
The tool compares the texts line by line using the "longest common subsequence" (LCS) algorithm — the same basic principle Git and other version control tools use to show a diff. A changed line is shown as one removed (old version) and one added (new version), since the tool compares whole lines rather than individual characters within a line.
Practical uses: comparing two versions of a text, code, or contract, seeing what changed between two drafts, or checking whether a copied text actually matches the original.
Frequently asked questions
Does the tool compare individual characters or whole lines?
Whole lines. A line that's changed is shown as one removed line (the old version) and one added line (the updated version), not as a character-by-character highlight within the line.
Does line order matter?
Yes. The diff algorithm takes order into account — a line that's simply moved will show as removed in one place and added in another.
Are my texts sent to a server?
No, the entire comparison happens locally in your own browser.