Web Capacity Analysis Tool

free utility to test the capacity of your web server

If you ask your website manager how many visitors you’ve had this week, chances are they’ll be able to tell you not just the totals, but the new visitors, loyalty figures – checking web statistics is addictive. They’ll probably have a nice Excel chart showing growth over time, with forecasts of future growth. A question that they’ll find harder to answer is how much traffic your system can actually handle. If you really hit the big time, will your servers stand up to the traffic?

Microsoft’s Web Capacity Analysis Tool (WCAT), is a free utility that you can use for load-generation. It plays back scripted HTTP requests against a Web server (or load-balanced server farm) and gathers statistics so you can analyse them. WCAT can simulate thousands of concurrent users making requests to a single web site or multiple web sites. The WCAT engine uses a script to define the set of HTTP requests to be played back to the web server.

Using the utility, you can set up any machines you have available as test clients, on each of which WCAT will spawn multiple virtual clients. The results are saved as an XML file that you can view using the XSL style sheet included in WCAT to see as tables in Internet Explorer. The report shows summaries including the number of transactions, CPU usage, and any errors. You can choose performance counters, view response-times, and see the statistics per-transaction and per-client.

You can download the 64 bit version of the utility from 64-bit WCAT , and the 32-bit version from 32 bit WCAT