Compare two texts and highlight differences
Diff Viewer compares two texts line by line, entirely in your browser — nothing is uploaded to a server. It's a simple positional comparison, not a true diff algorithm: it compares line 1 against line 1, line 2 against line 2, and so on, rather than realigning lines after an insertion or deletion. Inserting or removing a single line near the top will make every line after it show as changed, since positions no longer match up.
Is Diff Viewer free to use?
Yes, it's completely free with no signup required.
Does it support file upload, or only pasted text?
Only pasted text — there's no file picker or drag-and-drop upload.
Does it use a real diff algorithm like Git?
No — it compares lines by position (line 1 vs line 1, line 2 vs line 2, etc.) rather than realigning text after insertions or deletions, so a single added or removed line can make everything after it appear changed.
Can I download or copy the diff results?
No, there's no copy or export button for the diff output — you'd need to review it on screen.