Depict.ai - Amazon-quality product recommendations for any online store
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.
Outgrow eCommerce - Boost eComm sales with interactive product recommendations
Dynamic Yield - Personalization & customer experience management
Metisa - Product recommendations that learn as your customers shop
Optimizely - A/B testing you'll actually use.