Equal[iseR] is a frequency-domain solver for non-smooth systems of ODE/DAE targetting the vibration analysis of structural mechanical systems subject to unilateral and frictional contact occurrences. It is an adaptation of the well-known Harmonic Balance Method. It relies on [Equal]ity-based versions of the governing equations solved in a weighted [Resi]dual sense. Unilateral contact and friction commonly take the form of differential inclusions which can be recast into more conventional equality-based identities through the use of non-smooth projections. Such equations are then approximately transformed using classical weighted residual techniques. The resulting system of nonsmooth/nonlinear equations is solved using the classical Hybrid Powell solver.