It can be entirely self hosted, though there are options that use voice services from AT&T and Google. And of course any plugins that use cloud services would of course send data to the cloud. But it can be configured self contained.

Ok, rereading FAQ found "None of this information ever leaves the Pi" for information in my profile. Still interesting what cloud services are being used, but this probably is on a per-module basis.

It certainly seems to be per-module, for example: http://jasperproject.github.io/documentation/configuration/#...