STLView is described as 'A Free STL Viewer for Android and Windows'. There are more than 10 alternatives to STLView for Windows, Mac, Linux, iPhone and iPad. The best alternative is F3D, which is both free and Open Source. Other great apps like STLView are Magics (Paid), Free View Expert (Freemium), Netfabb (Freemium) and Viewshape (Free).
Netfabb is not just a viewer, it provides mesh edit, repair and analysis capabilities to everyone already being or aspiring to become part of this fantastic, growing, creative, high-tech industry called Additive Manufacturing, Rapid Prototyping or 3D Printing.
JNetCAD is a Java application for viewing and converting CAD data. It's free for non commercial or educational use. It supports reading 3DS, BGF, DXF, JT, OBJ and STL and writing DXF, EPS, JSON, JT, OBJ, 3D-PDF, STL and VGF.
The STL Viewer is FREE software for visualisation of STL or OBJ meshes created in packages such as 3D Studio Max, MAYA and Z Brush, modeled in CAD systems or generated from 3D digitalization of physical objects.