XTDS is a Java front-end to the different programs implementing the tensorial formalism developed in the Dijon group [see for instance: V. Boudon, J.-P. Champion, T. Gabard, M. Loëte, F. Michelot, G. Pierre, M. Rotger, Ch. Wenger, M. Rey, J. Mol. Spectrosc. 228 (2004) 620–634 ]. It allows the simulation and analysis of polyad systems for molecules of various symmetries (Td and Oh spherical tops like CH4 and SF6, C2v and C4v quasi-spherical tops like SO2F2 and SF5Cl, D2h molecules like C2H4). SPVIEW is a multiplatform Java application that allows graphical assignment of high-resolution molecular spectra. It is possible to load, display and manipulate experimental and simulated spectra (XY ASCII format) as well as stick spectra in various formats (including HITRAN format). Lines can be assigned graphically using the mouse. Assignments can also be modified or removed. Local simulations can be performed in order, for instance, to help assignment in partly resolved line clusters. SPVIEW is also able to produce peak lists from an experimental spectrum. Both software can be freely downloaded at the URL http://icb.u-bourgogne.fr/OMR/SMA/SHTDS.