How to configure Fiddler to listen to localhost?

Question

I want to monitor HTTP traffic between a process on my local machine and another (server) process, also running on my local machine.

How can I configure Fiddler to

Answer 1

Specific to Firefox, which does not go through Internet Options like IE, Chrome, and Edge do, you can use about:config to modify preferences, find the preference network.proxy.no_proxies_on and remove localhost from it.

This was the default setting for Firefox Developer Edition 66.0b2 and worked with Fiddler 5.0.20182.28034.

(Other listed solutions do work, this solution allows you to not change the host you are navigating to.)