Paste two versions of some text and see exactly what changed — added lines in green, removed lines in red. Everything is compared in your browser; nothing is uploaded.
How it works & your privacy: the two texts are compared line by line using a longest-common-subsequence diff — the same approach code tools use — so it finds the smallest set of additions and removals rather than just flagging everything after the first change. It all runs on your own computer; nothing you paste is uploaded. "Ignore case" and "ignore whitespace" affect only the comparison, not what's shown.