New physics facing LFU and LFV tests in B physics

Lepton flavor universality in the Standard Model and hints of its violation in neutral ($R_K$) and charged currents $(R_{D^{(*)}})$ in $B$ decays are presented. We discuss model independent features as well as several leptoquark scenarios which are well suited to fit current values of $R_K$ and/or $R_{D^{(*)}}$.