[en] Highlights: • A Monte Carlo code has been developed and validated using EGSnrc. • A radionuclide decay generator has been written and validated. • Detection efficiency can be calculated for High Purity Germanium detector. • A flexible and user friendly analysis software using MS Excel^® has been developed. • Functionalities and performances of the software are presented. - Abstract: At the JRC-Geel's RadioNuclide Metrology sector, a Monte Carlo code based on EGSnrc, and a general purpose calculation sheet implemented in Microsoft Excel^®, have been developed to make the quantitative gamma-ray spectrometry analysis of samples simpler and more robust. The further aim is that the software can be used by non-experts in gamma-ray spectrometry e.g. external researchers using JRC-Geel's facilities through the EUFRAT transnational access scheme. This paper presents the developed Monte Carlo software and the functionality included in the calculation sheet.