if you own a self-hosted wordpress website then you sometime wanted to know how the website performance are for other users. you can use these tools to test your website in terms of its network speed. kind of like a stress test.
use pingdom to test your website speed and also you can use RUM (real user monitoring) to scale your visitors satisfaction when visiting your site.
2. load impact
this site is useful if you want to test out how your website will performed when there are 50 simultaneous user visiting your website and they will give you the result so you can know which object are slowed in performance of your site
also display the speed network of your site
give your website ranking in terms of its speed using google and yahoo index for site speed.
stress test is a necessary things to know how your website fares against another. kind of like a standardization of website speed.