Diff Checker
Paste two versions of a text and see exactly what changed, line by line. Switch between a unified view and a side-by-side one, or tell it to ignore whitespace and case.
Settings
Compares automatically as you type.
Output
How it works
Your two texts are split into lines and compared with a longest-common-subsequence algorithm — the same family of technique behind most code-review diffs. Lines that appear in both stay plain, lines only in the first text are marked −, and lines only in the second are marked +.
The two checkboxes change how lines are matched, not how they are shown. "Ignore whitespace" collapses runs of spaces before comparing, and "Ignore case" lowercases everything first — handy when reformatting has shuffled the layout but the content is the same.
One honest limitation: this diff is line-based, so a single changed word marks the whole line as changed. It won't highlight the exact word inside the line. Very large texts (tens of thousands of lines) can also take a moment, since all the work happens in your browser rather than on a server.