Strange metals are a fascinating family of quantum materials, where charge transport differs considerably from Fermi liquid theory, the theory of conventional metals. Their resistivity scales linearly with temperature, while their frequency-dependent, ac conductivity shows frequency over temperature scaling. These are signatures of quantum criticality. At a quantum critical point, temperature is the only scale, which is why physical observables are scaling. This is not quite what is observed in strange metals: indeed, their linear in temperature resistivity is in fact not compatible with the simplest version of quantum criticality, and strong electronic interactions are thought to be responsible. On the other hand, gauge/gravity duality is a first-principle framework to capture the dynamics of strongly-coupled states of matter. It originates from string theory and maps gauge theory to Einstein gravity coupled to a number of matter fields. Thus, by solving the gravity equations, we can access the correlation functions of the dual field theory. In this doctoral project, we will study linear and nonlinear response of strongly-correlated metals using gauge/gravity duality.