In this talk I will give a brief review on the intrinsic link between the numerical renormalization group (NRG) and the density matrix renormalization group (DMRG) in terms of tensor networks. With respect to the NRG then, complete yet fully tractable many-body basis sets allow for textbook evaluations of physical properties of quantum impurity models such as dynamic correlation functions or quantum quenches. This, for example, also provides a direct link to optical absorption spectra, and provides a framework for a clean numerical treatment of Anderson orthogonality exponents in the thermodynamic limit. More generally, challenges in numerical complexity will be addressed, highlighting a recent algorithmic advance in terms of the generic implementation of non-abelian symmetries within tensor networks.