Web Application Stress Testing

I'm looking for a 3rd party app that can Stress Test my Web Application.

I'm looking for bottlenecks and potential break points on the Server side. I'm more interested in breakages than bottlenecks or performance issues.
I'd like to see how our Server side functionality performs under heavy usage. We have some file move functionality in particular on the Server side which has not been tested.

I'd like to schedule regular nightly tests too, so scripting is a requirement too or some sort of scheduling functionality.


Are there any reliable free tools out there?

I've come across the Microsoft ACT tool, I haven't got an installation yet however, anyone have experience with this? is it only available on the Enterprise edition of VS .NET?


There's also a free tool from msdn, it's pretty old however, Microsoft WAS web stress tool.

Here are some links that might help you.

Web Test Tools
Load Testing Tools
Stress Tools