The FDMNES code is user-friendly ab initio software that allows the simulation of X-ray absorption spectroscopy as well as X-ray resonant and nonresonant scattering spectroscopies. Here, the theoretical components of the code, the calculation steps and a typical example of its application are briefly presented. One of the main characteristics of the code is that two different techniques can be independently used to solve the electronic structure. The full-potential finite-difference method precisely applies for free shape potentials, while full multiple-scattering theory gives less precise but faster calculations. Calculations can be applied to all classes of materials. Especially adapted for the low-energy range of the spectra around the absorption range, its relativistic self-consistent density functional theory (DFT) approach makes it efficient for the K edges of all elements and the L_2,3 edges of heavy elements. A time-dependent DFT extension expands the scope of the software to other edges.