Optimizely - A/B testing you'll actually use.
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
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.
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
VWO - Use VWO to tweak, optimize & personalize your website with minimal IT help.
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.