Optimizely - A/B testing you'll actually use.
AbTest.io - A free url shortener with A/B testing features
VWO - Use VWO to tweak, optimize & personalize your website with minimal IT help.
PreFlight - Preflight is an Automated Web Testing tool. Allows everyone to automate Web UI tests.
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.
GoodUI Fastforward - Lift your conversion rate with repeatedly AB tested patterns