Algolia - Algolia's Search API makes it easy to deliver a great search experience in your apps & websites. Algolia Search provides hosted full-text, numerical, faceted and geolocalized search.
Optimizely - A/B testing you'll actually use.
ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.
VWO - Use VWO to tweak, optimize & personalize your website with minimal IT help.
Klevu - Klevu offers instant site search solution for eCommerce stores.
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.