Optimizely is a lower cost entry tool for anyone looking to do website testing. While their pricing structure has changed over the years it still is a pretty cost effective solution. It is easy to get tests up and running within 5 minutes once you have code placed on your site.
I love the drag and drop features of Optimizely. It makes it very easy to make simple changes to do landing page testing for my paid search campaigns. It also frees up dev time for our web team. Also, The findings from Optimizely tests are so valuable for an end customer experience.
WooCommerce - A freely available eCommerce plugin that enables shop facilities on your WordPress website. Functionality enabling extensions & beautiful themes available.
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.
VWO - Use VWO to tweak, optimize & personalize your website with minimal IT help.
Shopify - Shopify is a powerful ecommerce platform that includes everything you need to create an online store and sell online. Try it free for 14 days.
AB Tasty - AB Tasty is an all-inclusive platform for conversion rate optimization, personalization, customer activation, and testing.