OpenCart - A free shopping cart system. OpenCart is an open source PHP-based online e-commerce solution.s
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.
PrestaShop - Create your online store with PrestaShop's free shopping cart software. Build an ecommerce website for free and start selling online with hundreds of powerful features.
Optimizely - A/B testing you'll actually use.
WooCommerce - A freely available eCommerce plugin that enables shop facilities on your WordPress website. Functionality enabling extensions & beautiful themes available.
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.