The here presented GLAciology NUmerical SImulation Toolbox (GLANUSIT) is a software application which provides a user friendly environment for the numerical simulation of large ice masses evolution. The graphical user interface has been developed in MATLAB while the core of GLANUSIT contains the original FORTRAN codes, which develop the specific numerical methods for the solution of the complex shallow ice model. This highly nonlinear model governs the coupled thermodynamical and hydrodynamical processes. The global algorithm mainly consists on a fixed point iteration between the different subproblems. The numerical solution of each subproblem requires specific techniques, which are not common in present software packages, as for example the part of moving boundaries solvers included in the code. Finally, a practical case study with real data is presented.