In my talk, I shall consider minimal anomaly free U(1) extensions of the Standard Model with three generations of right-handed neutrinos and a complex scalar. Then, I shall show that the parameter space of a class of such models is heavily constrained by the electroweak precision test and the LHC data. I shall also discuss the Green-Schwarz anomaly cancellation mechanism in this context and its future prospects. Finally, I shall discuss possible outlooks and future directions in terms of dark matter and collider signatures