CUFSM is the Constrained and Unconstrained Finite Strip Method and was originally developed by Ben Schafer in 1997. For an arbitrary thin-walled cross-section CUFSM can efficiently provided all cross-section and member elastic buckling modes and loads for any applied end action (compression, bending, warping, etc.). CUFSM provides both the semi-analytical finite strip method for creation of the cross-section signature curve as well as the generalized finite strip method for other end boundary conditions (e.g. clamped ends). Uniquely, CUFSM provides a complete implementation of the constrained finite strip method which allows the user to perform quantitative modal decomposition and identification which, e.g., provides a precise means to separate local, distortional, and global buckling modes in thin-walled members. CUFSM includes tools for generalized beam-column loading and analysis. A number of supplementary tools have been added to CUFSM including development of plastic surfaces for cross-sections under arbitrary load, independent global buckling analysis with classical beam formula, and an interface to generate ABAQUS input files with cross-section imperfections based on CUFSM buckling modes.