I came across two new (to me) tools today for testing websites, Alkaline and Load Impact.
Alkaline is a new Mac application from Litmus that allows you to “tests your website designs across 17 different Windows browsers right from your Mac desktop.” It works as a standalone app, or with Coda and TextMate using plugins. The free version tests in Firefox and Internet Explorer 7, and if you sign up for a paid Litmus account you can test in all 17 browsers.
Load Impact is an online testing tool to simulate high user loads. There is a free option allowing you to simulate a low load level, and the test results help you see which assets (CSS, images, JavaScript) are slow-loading or problematic as well as how the site performs the more users hit it at once. I don’t see this replacing YSlow for quick and dirty speed tests and load optimization, but it could be an awesome tool for larger websites that need to do “real” stress and load tests.
The Sensible Leader 