Our understanding of non-equilibrium critical phenomena is far from that of their equilibrium counterparts, although they are far more common in physics and other sciences. Characterizing non-equilibrium universality classes has become one of the main challenges of statistical physics, but is hindered by the scarcity of efficient analytical tools. In this context, the nonperturbative renormalization group appears as a generic and powerful method to investigate non-equilibrium systems, which have allowed us to make progress, in particular in the fields of reaction-diffusion processes and growth phenomena, which we will present. These analyses have indeed unveiled that nonperturbative effects turn out to be crucial to understand the properties of these systems, which we will discuss.