cspy is an open source Python package that gathers some algorithms to solve the (resource) Constrained Shortest Path (CSP) problem. The CSP problem has been studied in the mathematical optimisation literature as allows the modelling of a wide range of problems. They have proven useful in a wide variety of problems including: the vehicle routing problem with time windows, the technician routing and scheduling problem, the capacitated arc-routing problem, on-demand transportation systems, aircraft scheduling, and, airport ground movement.