I figured it all out. Strange that this information is treated as if it is some secret no one wants to talk about.

Google moved their GIS data into Google Maps API. You could try this: https://developers.google.com/maps/documentation/elevation/overview

Similarly, Microsoft has their GIS data in Azure Maps API. You could try this: https://docs.microsoft.com/en-us/azure/azure-maps/how-to-request-elevation-data​

Arc…

I would like to build an application where I can easily download various GIS data to create my own maps. 

What's the best way in? I'm very familiar with programming, graphics and GIS, but I wonder what's the best platform to begin with. Do you have any experience with MapBox? They seem to provi…