This paper presents a software package, called GTAexpress, to handle structured continuous-time Markovian models expressed using generalized tensor algebra, also known as, Kronecker descriptors. The proposed software package has the most advanced methods to provide stationary and transient solutions as well as some basic structural properties of models represented as a sum of generalized tensor products. Other software tools already provide some approaches based on tensor representation, like, PEPS and SMART. However, such tools are bounded to a specific modeling formalism. The basic idea of GTAexpress is to provide Kronecker descriptor-based solutions that can be easily used as a package in new tools or as a library in the existing high-level formalisms tools.