This is a demo-application illustrating how the Wagner-Fischer alignment (Wagner and Fischer 1974) between two sequences is computed. The interactive application which computes this code has been tested on Google Chrome and Firefox and should work out of the box by simply opening the HTML file in your browser. The screen video gives an additional illustration of the appearance of the application. The script was originally written for education purposes and may turn out to be useful in this context, since it allows the users to review each step of the Wagner-Fischer algorithm in different pastes.