PyHeatDemand is an open-source Python package for processing and harmonizing multi-scalemulti-type heat demand input data for constructing local to transnational harmonized heat demand maps (rasters). Knowledge about the heat demand in megawatt hours per area and per year of a respective building, district, city, state, country, or even on a continental scale is crucial for an adequate heat demand analysis or planning for providing power plant capacities. Mapping of the heat demand may also identify potential areas for new district heating networks or even geothermal power plants for climate-friendly heat production.