Question 1

How are the differences computed?

Accepted Answer

The tool compares the texts line by line using a longest-common-subsequence algorithm — the same family of algorithms used by git diff. Unchanged lines are matched up, and the remaining lines are shown as removals (red) and additions (green).

Question 2

What is the difference between the unified and side-by-side views?

Accepted Answer

The unified view interleaves removals and additions in one column, like git diff or a patch file — compact and good for reviewing changes. The side-by-side view shows the original on the left and the modified text on the right with changed lines aligned, which makes structural edits easier to scan.

Question 3

Can it handle large files?

Accepted Answer

Yes, within reason. Unchanged leading and trailing lines are skipped instantly, so the expensive comparison only runs on the changed middle section. For extremely large, almost entirely different inputs the tool falls back to showing the section as one replaced block instead of freezing the tab.

Question 4

Does it diff individual characters within a line?

Accepted Answer

No — the comparison is line-based: a line with any change is shown as a removal plus an addition. Line-based diffs match how code review and patch tools work, and keep the output predictable for large inputs.

Question 5

Are the texts I compare uploaded anywhere?

Accepted Answer

No. Both texts are compared entirely inside your browser; nothing is uploaded or tracked, and the tool works offline once the page has loaded — safe for confidential documents, configuration files, and code.

Diff Viewer

FAQ