A wireless charging system with foreign object debris detection, the system comprising: at least one wireless energy transfer source including a source resonator configured to generate an oscillating magnetic field; and a foreign object debris detection system comprising: at least one magnetic field sensor (202, 204, 502, 602, 604, 606), and at least one readout circuit (506, 508, 608, 610, 704, 702) to measure electrical parameters of the at least one magnetic field sensor, characterized in that: the at least one magnetic field sensor is positioned within the oscillating magnetic field generated by the source resonator of the wireless charging system and is configured to measure magnetic field perturbations of the oscillating magnetic field generated by the source resonator of the wireless energy transfer source; wherein the magnetic field perturbations indicate the presence of metallic foreign object debris, and wherein the foreign object debris detection system is configured to verify that no metallic foreign object debris has moved onto the source resonator during charging by the wireless energy transfer source. at least one wireless energy transfer source including a source resonator configured to generate an oscillating magnetic field; and a foreign object debris detection system comprising: at least one magnetic field sensor (202, 204, 502, 602, 604, 606), and at least one readout circuit (506, 508, 608, 610, 704, 702) to measure electrical parameters of the at least one magnetic field sensor, characterized in that: the at least one magnetic field sensor is positioned within the oscillating magnetic field generated by the source resonator of the wireless charging system and is configured to measure magnetic field perturbations of the oscillating magnetic field generated by the source resonator of the wireless energy transfer source; wherein the magnetic field perturbations indicate the presence of metallic foreign object debris, and wherein the foreign object debris detection system is configured to verify that no metallic foreign object debris has moved onto the source resonator during charging by the wireless energy transfer source. at least one magnetic field sensor (202, 204, 502, 602, 604, 606), and at least one readout circuit (506, 508, 608, 610, 704, 702) to measure electrical parameters of the at least one magnetic field sensor, characterized in that: the at least one magnetic field sensor is positioned within the oscillating magnetic field generated by the source resonator of the wireless charging system and is configured to measure magnetic field perturbations of the oscillating magnetic field generated by the source resonator of the wireless energy transfer source; wherein the magnetic field perturbations indicate the presence of metallic foreign object debris, and wherein the foreign object debris detection system is configured to verify that no metallic foreign object debris has moved onto the source resonator during charging by the wireless energy transfer source. the at least one magnetic field sensor is positioned within the oscillating magnetic field generated by the source resonator of the wireless charging system and is configured to measure magnetic field perturbations of the oscillating magnetic field generated by the source resonator of the wireless energy transfer source; wherein the magnetic field perturbations indicate the presence of metallic foreign object debris, and wherein the foreign object debris detection system is configured to verify that no metallic foreign object debris has moved onto the source resonator during charging by the wireless energy transfer source.