Fiddler is a fantastic tool for assisting in debugging HTTP request/responses.
However, god forbid you try to scan the activity list for a specific request when other applications are constantly making outbound HTTP/S calls. Within a matter of seconds, the result view is chock full of crap.
I toyed around with the “custom rules” in Fiddler before, but lost them somewhere along the way - upgrades, new machines, etc.
Today, I decided to finally tackle it again. However, I wanted to add the rule as an option in the menu that is enabled by default, so that as soon as I launch Fiddler, it is automatically filtering the request output.
Start by launching Fiddler, and going to Rules | Customize Rules in the menu bar.
This will launch the Fiddler ScriptEditor.
Inside of the Handlers class, add the following code, which sets up a new menu item under “Rules”, called “Show Localhost Only”, with a default of true:
public static RulesOption("Show Localhost Only")
var m_ShowLocalhostOnly: boolean = true;
Now, scroll down until you find the OnBeforeRequest method. Looks like this:
static function OnBeforeRequest(oSession: Session) {
Inside of that method, add the following conditional:
if (m_ShowLocalhostOnly && oSession.host.indexOf("localhost.com") == -1) {
oSession["ui-hide"] = "true";
}
Locally, when I’m developing, I have hostnames setup for all of my sites using localhost.com as the TLD. If you utilize something a little different, just modify the indexOf method inside of the if block.
Now, when I launch Fiddler, all of my requests are filtered out, by default, except for entries to *.localhost.com (Except for the Fiddler update check, because apparently that happens before the rule gets applied).
And, if I need to look at the other crap being logged, I can just toggle the menu item and turn it off for the duration of that Fiddler session.
This post, "Creating a default Fiddler rule for Localhost traffic only", first appeared on https://www.codingwithcalvin.net/creating-a-default-fiddler-rule-for-localhost-traffic-only/