CtrlView is described as 'fast, compact, powerful viewer/converter for different 2D/3D raster/vector file formats with the format recognition system. It means that CtrlView analyses content of the file and determines its format'. There are three alternatives to CtrlView for Windows, Linux and Mac. The best alternative is GLC_Player, which is both free and Open Source. Other great apps like CtrlView are noesis (Free) and open3mod (Free, Open Source).
Noesis is a tool for previewing and converting between hundreds of model, image, and animation formats. It utilizes a robust plugin system, with support for native extension modules and Python scripts.
A free, Open-Source 3D Viewer designed to make it all easier. Massive 3D Format support Free and powerful 3D Viewer for more than 40 file formats, including OBJ, 3DS, BLEND, STL, FBX, DXF, LWO, LWS, MD5, MD3, MD2, NDO, X, IFC and Collada.