Flavor changing neutral currents and properties in top quark events at the CMS and ATLAS experiments

The latest searches for flavor changing neutral currents (FCNCs) and measurements of properties in top quark events at the CMS and ATLAS experiments are presented. The vast amounts of proton-proton collision data recorded during the CERN LHC Run 2 at $\sqrt{s}=13$~TeV provide excellent opportunities to test the standard model (SM) with increasingly high precision and search for subtle deviations from the SM expectation. Tight constraints on top quark FCNC decay branching fractions are derived, and asymmetries of observables sensitive to new physics are measured.