I am currently at the London Tester Gathering Workshops in a session being hosted by Bill Matthews. He is showing the attendees how to use Zap Proxy. During the class he mentioned that you can hook your existing WebDriver checks into a proxy. Something I also mentioned in my recent "WebDriver Beyond Checks" post.
So I thought I would create a quick post showing you how you can do this. I am not using Zap, instead I am using Fiddler, but you just need the right proxy url and change accordingly.
Here is how you do it in C# using Firefox and Chrome drivers.
Here is how you do it in Java.
There you go, you can now add a proxy to your WebDriver checks, and collate lots of information to explore from various proxies available such as, BrowserMob, Fiddler and ZapProxy.