pymol is described as «PyMOL is a powerful and comprehensive molecular visualization product for rendering and animating 3D molecular structures» and is an app in the education & reference category. There are more than 10 alternatives to pymol for a variety of platforms, including Mac, Windows, Linux, Android and Wine. The best alternative is UCSF Chimera, which is free. Other great apps like pymol are BioBlender, Calistry.org, Jmol and Rasmol.