Zscaler Support may ask you to provide HTTP headers when troubleshooting certain issues. The HTTP headers identify the specific URL the browser accessed when you opened a web page. You can use Mozilla's Inspector tool to capture HTTP headers in Mozilla Firefox version 88.0.1.
Process:
Open Mozilla Firefox, load your desired website. example www.facebook.com
on the top-right click on Application Menu > More Tools > Web Developer Tools.
or
press CTRL + SHIFT + i.
click on Network tab and select one of the element that loads and select Save All as HAR.