How to analyze HTTP headers generated&received
Analyzing HTTP headers is a great way to debug websites. This is the easiest way to check what data was actually returned by Ajax request or find out if a website redirected us to another place. You can also check POST and GET fields sent by the browser and even modify then on the fly.
There are two great Firefox plugins I use and I want to recommend you.
First is Live HTTP Headers (click to download)
This add-on was downloaded over 2 million times and is always compatible with the newest Firefox.
The other one, but one I like most, is Tamper Data (click to download). This is what I use for everyday debugging.
After you install it just click Tools->Tamper Data and then reload a website.
