The definition of user experience (UX) is broad and covers several aspects. The job of any programmer is very specific and demanding. He/she uses different systems or tools to carry out their programming tasks. We consider a programmer as a specific case of user, who employs programming environments and other software development artifacts. We therefore consider this particular kind of UX as Programmer eXperience (PX). Several authors have defined different aspects of PX, including, among others, language features, programming learning factors or programmer performance. Usability is a relevant aspect of UX, as well as an important aspect of programming environments. Heuristic evaluation is an inspection method that allows evaluating the usability of interactive software systems. We developed a set of heuristics following the methodology proposed by Quiñones et al. We defined a new set of 12 specific heuristics that incorporate concepts of UX and usability of programming environments. These heuristics have been validated following also that methodology. The results obtained in different effectiveness criteria were satisfactory. However, the set of heuristics could be further refined and validate in new scenarios or case studies.