  HarmonicBalance.jl is a publicly available Julia package designed to simplify
and solve systems of periodic time-dependent nonlinear ordinary differential
equations. Time dependence of the system parameters is treated with the
harmonic balance method, which approximates the system's behaviour as a set of
harmonic terms with slowly-varying amplitudes. Under this approximation, the
set of all possible steady-state responses follows from the solution of a
polynomial system. In HarmonicBalance.jl, we combine harmonic balance with
contemporary implementations of symbolic algebra and the homotopy continuation
method to numerically determine all steady-state solutions and their associated
fluctuation dynamics. For the exploration of involved steady-state topologies,
we provide a simple graphical user interface, allowing for arbitrary solution
observables and phase diagrams. HarmonicBalance.jl is a free software available
at https://github.com/NonlinearOscillations/HarmonicBalance.jl.
