Optimizely - A/B testing you'll actually use.
BucketListly - The most beautiful & advanced bucket list you will ever have
VWO - Use VWO to tweak, optimize & personalize your website with minimal IT help.
Extension Boilerplate - Build cross browser extensions for Chrome, Firefox & Opera
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.
YouTube Vanced - Vanced is a modded version of YouTube with many features such as adblocking and background playback