Selectorless crossbar arrays of resistive randomaccess memory (RRAM), also known as memristors, conduct large sneak currents during operation, which can significantly corrupt the accuracy of cross-point analog resistance (M t ) measurements. In order to mitigate this issue, we have designed, built, and tested a memristor characterization and testing (mCAT) instrument that forces redistribution of sneak currents within the crossbar array, dramatically increasing M t measurement accuracy. We calibrated the mCAT using a custom-made 32 × 32 discrete resistive crossbar array, and subsequently demonstrated its functionality on solid-state TiO 2-x RRAM arrays, on wafer and packaged, of the same size. Our platform can measure standalone M t in the range of 1 kΩ to 1 MΩ with <;1% error. For our custom resistive crossbar, 90% of devices of the same resistance range were measured with <;10% error. The platform's limitations have been quantified using large-scale nonideal crossbar simulations.