123D Sculpt is described as 'Free for a limited time!' and is a 3D Painting app in the photos & graphics category. There are more than 25 alternatives to 123D Sculpt for a variety of platforms, including Windows, Mac, Linux, Android and iPhone. The best alternative is Blender, which is both free and Open Source. Other great apps like 123D Sculpt are ZBrush, Bforartists, Cinema 4D and 3D-Coat.
123D Sculpt is mainly a 3D Modeler but alternatives to it may also be 3D Painting Apps or 3D Animators. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of 123D Sculpt.