Automated DEM Process

I intend to work on DEM creation and want to automate this process. Does there exist any API that could help me imitate the process mentioned in ? I want the DEM of large area, so any suggestions in automating any stage of the pipeline, from downloading to getting the DEM would be highly welcomed.
Thanks for the help.

please stop making multiple topics on the same issue. We have several topics on DEM creation already.