How to view HTTP headers in Mozilla Firefox
To view the request or response HTTP headers in Mozilla Firefox, take the following steps :
1. In Firefox, visit a URL, right-click, select Inspect Element
to open the developer tools.
2. Select the Network
tab or directly press Ctrl+Shift+E together from your computer keyboard.
3. Reload the page, select any HTTP request, and the HTTP headers will be displayed on the right panel.