"Grid3D Toolbox" is a set of command line tools for visualization and analysis of the results of molecular simulations based on 3-dimensional density maps (grids). Currently, the tools only work with the simulation trajectories generated by the GROMACS simulation package (http://www.gromacs.org/).
The generated density maps are saved in the Grid3D native .g3d format and can be visualized using a third party data visualization software.