The computer program CASPER and its algorithms are described. The program is aimed at facilitating the determination of structures of oligosaccharides and regular polysaccharides, requiring as input either the one-dimensional 1H or 13C NMR spectrum or the 2D C,H-correlation NMR spectrum together with information on components and linkages. The databases, the method of simulating spectra, options of the program, and techniques for faster calculations are described as well as an example of a structural determination.