XML API documentation or .NET source?

Since we are looking to deploy to .NET core, we would obviously need to use the XML directly,
or compile for .NET core.

Looking for the raw XML API documentation (or possibly JSON, but presume not).
Looking for source for .NET API source.  (wasn't this open a few years back?)


I was sure there was XML documentation around, but can't find it now.

If none, will walk through the Py or PHP solutions.