Monday, February 14, 2011

Load testing with Fiddler

For one of our projects, we wanted to do some load testing to validate if our infrastructure was sufficient. We decided not to use the Visual Studio Load testing features.

Instead we choose StressStimulus, a free Fiddler plug-in for easy load testing of web applications.

StresStimulus plays back HTTP requests recorded in Fiddler to create high concurrency workload on web applications. You can configure virtual users, think time, and number of test iterations or test duration.

After test completion, StresStimulus determines average performance of the test scenario. It breaks down response times of every page between server and network times to identify areas with scalability problems.

StresStimulus can be downloaded at It is free, allows unlimited virtual users, and no registration is required.

Remark: When we tried to install the plugin on a 64bit machine, the installation failed. This is a known bug and the problem will be fixed in the next release. You can already download the alpha here.


Anonymous said...

Why not VS Load Testing?

Vadim Kleyzit said...

Thanks for using StresStimulus. The bug with installing on 64-bit OS is fixed in the latest version, which also added load testing graphs.

On the question in the previous comment: VS Load Testing is a great tool, but if you need more that 250 virtual users, then besides Visual Studio 2010 Ultimate Edition you would need to purchase Load Test Virtual User Pack 2010. In that respect, StresStimulus is totally free and does not restrict virtual users.

Bart Wullems said...

In regards to the VS Load Testing question, we decided not to use the Load testing features because of the licensing cost. For the testing we needed to do, StressStimulus did the job perfectly.

Vadim Kleyzit said...

You may be interested to know that today we released a new version of StresStimulus that is designed to make load testing easier. It can also stress test dynamic websites. Read more about the new features in this blog.

Anonymous said...

StresStimulus is not free

Anonymous said...

StresSimulus is not free. In fact, it's quite expensive. Another option is to select several requests from the sessions list in Fiddler, and then use SHIFT-R. You can then replay those requests numerous times. It's a bit simplistic, but it's free and easy.

Vadim Kleyzit said...

Option to switch to a free edition is located in StresStimulus main menu. Also, StresStimulus's web site domain has been changed to

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