Amplify is a middleware library for Ising machines developed by Fixstars. Ising machines are specialized for solving optimization problems described by quadratic polynomials of binary variables. Starting with the quantum annealing machine by D-Wave Systems, various types of Ising machines implemented with digital circuits and GPUs have been announced. This middleware is used as an intermediate layer between hardware and applications using Ising machines. We provide various functions that improve the convenience of the machines and enable highly efficient development of application software.