TesseRACt computes concentrations of simulated dark matter halos from volume information for particles generated using Voronoi tesselation. This technique is advantageous as it is non-parametric, does not assume spherical symmetry, and allows for the presence of substructure. TesseRACt accepts data in a number of formats, including Gadget-2 (ascl:0003.001), Gasoline (ascl:1710.019), and ASCII, and computes concentrations using particles volumes, traditional fitting to an NFW profile, and non-parametric techniques that assume spherical symmetry.