No network timing split available

Why can't I see timing split for my API calls in API performance or other pages?

Zipy uses the Resource Timing API to retrieve information about the timing of various resources loaded by a web application. However, it is restricted by the cross-origin security policies enforced by browsers. By default, only resources loaded from the same origin as the web application are accessible for timing information.

To overcome this limitation, you can enable extended data collection for cross-origin resources subject to Cross-Origin Resource Sharing (CORS). This can be achieved by including the "Timing-Allow-Origin" HTTP response header in your cross-origin resources. For instance, you can grant access to resource timing for any origin by setting the header value to "Timing-Allow-Origin: *". Additional details about CORS can be found in the MDN Web Docs.