V_Sim visualizes atomic structures such as crystals, grain boundaries and so on (from many file formats, binary or plain text, see the sample page). The rendering is done in 3D with colored sphere to represent the atoms. The user can interact through many functions to choose the view, load densities, draw planes... Moreover V_Sim allows to export the view as image in PNG, SVG or more formats. It uses GTK2 or GTK3 (lib and dev files version 2.4 or greater) and OpenGl (lib and dev files), no other dependencies are required. It is programmed in C and is aimed to run on *nix systems (including MacOSX) and compile also on Win32 platforms.