Compares two texts line by line using the classic longest common subsequence (LCS) dynamic-programming algorithm — the same idea behind the Unix diff command. Removed lines are shown on a red background with a - prefix, added lines on a green background with a + prefix, and unchanged lines in gray, together with counts of added and removed lines. Texts up to 2000 lines each are supported.
Great for reviewing config changes, comparing document versions or spotting edits between two code snippets. Everything runs locally in your browser — nothing is sent to any server.