Fiddler

Ostensibly this page is about Fiddler but actually it's about debugging web connections. When I say "Fiddler" I mean "Fiddler Classic".

This is a great page: Best Fiddler Alternatives]

What is Fiddler

It's a desktop app. Fiddler acts as a proxy, it runs on your Windows (or Mac or Linux) desktop and captures traffic going between your browser and a remote website so that you can see what is going on. I remember trying it out a couple times at different jobs but nothing struck me as truly great about it.

You can do pretty much the same thing with Wireshark, I think. Fiddler is just tuned for web whereas Wireshark is generic network data capture.

I got as far as putting mitmproxy on a Linux box and pointing my browser at it, but I can't remember why I did that. I just remember that it worked. See docker/mitmproxy on cc-testmaps. It works amazingly well in fact. You have to install a cert in your Firefox browser, so that it trusts mitmproxy for HTTPS traffic. After that, you're good! Amazing. (Did I say that?)

HTTP headers

I need to see them, but they are visible in Chrome.

• F12
• Network tab
• Reload the page, watch all the network activity
• Pick a line in the left pane
• Switch from Preview to Headers in the right pane, there you go.