It's really useful to understand how request and response headers work, and what they mean to the browser and the server. You can find some interesting stuff in there. For example, when your Web browser asks a server for a page, it may inform the server it's able to receive and understand a compressed response (Accept-Encoding: GZIP, deflate). Other critical information, such as caching directives and character sets are included in request and response headers.

LiveHTTPHeaders installs into Firefox and shows you both the request and response headers sent between your browser and the server. It's that simple, and very useful indeed, for diagnosing thorny problems relating to proxies, caching, compression, and character sets.

Microsoft Web Application Stress Tool
It makes no difference if you program Java, Perl, PHP, .NET, or whatever. It makes no difference if you love or hate the Redmond giant, you need this Microsoft software.

You've built your awesome new Web server application and it's collapsing under the load when more than ten people use it, despite running on a server with dual Opteron CPU's and 12 GB of RAM. You're scared, because the boss expects 3,000,000 unique visitors to this great new system on the first day of its public launch. Who you gonna call? How about Microsoft?

Microsoft Web Application Stress Tool is a free tool from Microsoft (yes you heard right) that allows you to stress test your Web server by simulating multiple clients sending thousands of simultaneous requests to the server. Microsoft Web Application Stress Tool can record your live usage of a Web browser and play it back, or let yo manually edit and customize the requests sent to the server.

Once you've set up your script, you can execute the stress test against your server. Using a variety of parameters and options, you can configure how long the test should run. And, you can configure the number of concurrent connections including the number of threads to run, and the number of sockets to use per thread.

You can introduce random delays, and have a warm-up and cool down so that the real testing is done when the server is fully cached and running at optimal speed. Once the test has run, a detailed report is provided showing all sorts of interesting stats, including the number of requests per second the server was able to respond to.

It's fascinating to measure the performance of various application servers, hardware and network configurations, and to compare them.

Microsoft Web Application Stress Tool really is a great piece of software. Most amazing is, this powerful software is available as a free download. Whoever said Microsoft never gives anything away?

IBM Page Detailer
IBM Page Detailer is a real surprise.

Page detailer shows the complete conversation between client and server over time, and gives an entirely new perspective on understanding how browser and server interact.

Here's how IBM describes Page Detailer on the IBM Alphaworks Web site:

IBM Page Detailer is a graphical tool that enables Web site developers and editors to rapidly and accurately assess performance from the client's perspective. IBM Page Detailer provides details about the manner in which Web pages are delivered to Web browsers. These details include the timing, size, and identity of each item in a page. This information can help Web developers, designers, site operators, and IT specialists to isolate problems and improve performance and user satisfaction.

IBM Page Detailer places a probe in the Windows Socket Stack to capture data about timing, size, and data flow. It then presents the collected data in both graphical and tabular views, clearly showing how the page was delivered to the browser.

IBM's rather dry description of Page Detailer provides the facts but doesn't bring across the magic of Page Detailer.