Los Alamos Grid Toolbox (LaGriT) is a library of user callable tools that provide mesh generation, mesh optimization and dynamic mesh maintenance in two and three dimensions. LaGriT is used for a variety of geology and geophysics modeling applications including porous flow and transport model construction, finite element modeling of stress/strain in crustal fault systems, seismology, discrete fracture networks, asteroids and hydrothermal systems. The general capabilities of LaGriT can also be used outside of earth science applications and applied to nearly any system that requires a grid/mesh and initial and boundary conditions, setting of material properties and other model setup functions. It can also be use as a tool to pre- and post-process and analyze vertex and mesh based data.