LoadFocus - Cloud Testing Infrastructure | Cloud Testing Services and Tools for Websites & APIs.
Optimizely - A/B testing you'll actually use.
Loader.io - Loader.io is a simple cloud-based load testing service
VWO - Use VWO to tweak, optimize & personalize your website with minimal IT help.
Loadster - Loadster is a full-featured load testing solution for websites, web apps, and web services.
Google Analytics - Improve your website to increase conversions, improve the user experience, and make more money using Google Analytics. Measure, understand and quantify engagement on your site with customized and in-depth reports.