Does anyone have a categorized Geographic coordinate system List?

We are making a custom desktop application which will project a selected GDB or shapefile to a selected coordinate system. This will be a custom app since most of the users will not have access to GIS or are not even GIS people. The projection will run on a server, which will have the tools.

Problem is, we need the user to specify the projection. Although the list of projections are available (https://developers.arcgis.com/rest/services-reference/projected-coordinate-systems.htm), it is not categorized… Imagine having a dropdown with 5000 items… So we are thinking 3 levels, like in ArcGIS… But I can’t find those categories anywhere. I was hoping an excel file with 4 columns – The WKID, WK Text, Parent, System. This could work well I believe. Unless there is a library somewhere available?