Yes, microwaves are safe when the cord is unplugged. When you unplug the microwave, you are disconnecting its power supply, and it will not be able to generate microwaves or operate in any way. Therefore, there is no risk of it causing harm or starting a fire when it is not connected to a power source.
However, it's important to note that some microwave models might have a residual electrical charge stored in certain components even after being unplugged. This residual charge is generally minimal and not dangerous for normal use. But if you are planning to disassemble or repair the microwave, it's best to allow it to sit unplugged for a while to let any remaining electrical charge dissipate. Additionally, for any repairs, it's recommended to seek assistance from a qualified professional.
When the microwave is not in use, it is always a good practice to unplug it or keep it disconnected when not needed to save energy and minimize any potential risks associated with electrical appliances.