What is The Web Browser Plugin Used to View Message Traffic?

What is the name of the IE plug in that someone can download (I think from Microsoft) that lets a developer (well, anyone who gets the plug-in, actually) to view the message traffic that goes on behind the scenes from the browser to the server? I saw this one in action but I forget its name. And I think, for the FireFox broswer, you can simply turn it on somehow without getting a plug in.

It cuts the browser window in half horizontally and the bottom half is also divided vertically and you can see the GET and POST messages as well as the complete header information that is sent to the server from the browser across the internet.

The add-on I prefer and suggest to use for tracking messages is "Alert Box" because it helps to track not only the messages but the webpage changes and pop-up when any new updates comes.

I hope this will prove helpful

There is one more add-on which works entirely magnificent with my website i.e. "httpfox 0.8.11".

I always prefer Alert Box to View Message Traffic