MySQL - The world's most popular open source database
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.
PostgreSQL - PostgreSQL is a powerful, open source object-relational database system.
Optimizely - A/B testing you'll actually use.
SQLite - SQLite Home Page
Smartlook - Qualitative analytics for websites and mobile apps Start understanding the 'whys' of your users' behaviors with clear, visual insights. With session recordings and event tracking, you get the complete picture.