Phase-change thermal diodes rectify heat transport much more effectively than solid-state ones, but are limited by either the gravitational orientation or one-dimensional configuration. Here, we report a planar phase-change diode scalable to large areas with an orientation-independent diodicity of over 100, in which water/vapor is enclosed by parallel superhydrophobic and superhydrophilic plates. The thermal rectification is enabled by spontaneously jumping dropwise condensate which only occurs when the superhydrophobic surface is colder than the superhydrophilic surface.Analogous to the electronic diode, a thermal diode transports heat with a strong directional preference. Thermal diodes are useful in a variety of applications, such as heat distribution in spacecrafts, 1 thermal regulation during energy harvesting, 2 thermally adaptive building materials, 3 and potentially phononic computing. 4 The effectiveness of a thermal diode is measured by the rectification coefficient (diodicity),