HDG3D: This is a Matlab implementation of the Hybridizable Discontinuous Galerkin method on general tetrahedrizations of polyhedra in three dimensional space. The code includes tools to solve variable diffusion and convection-diffusion equations. The code was developed by the numerical group Team Pancho at the Department of Mathematical Sciences at the University of Delaware. The code is fully documented, not too tough to use, and quite easy to modify if you take your time to learn how degrees of freedom are counted and what’s the general idea of HDG. In the near future, we’ll add some worked out examples and more capabilities that are being developed.