xSort is a free card sorting application for Mac OS X aimed at user experience professionals and social scientists. Visual environment simulating a table with cards (and outline view). Supports open, semi-open and closed exercises. Supports sub-groups (participants can put groups inside groups). Control every aspect of the exercise (sorting type, cards placement, etc.). Statistical results (cluster tree, distance table, etc.) updated in real time. Displays individually all the info related to an individual session.