+-------+ +----------------+ +------------+
|Browser|<==A==>| Visited server |<==B==>| ID service |
+-------+ +----------------+ +------------+
The client data acquisition is done through A (AJAX), then that info is sent through B (API call) to get the identity. The browser doesn't interact directly with the ID service.
The data acquisition scripts would be served directly by the web sites.
The data acquisition scripts would be served directly by the web sites.