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.
Hawk Search - Site-search engine for eCommerce platforms.
Dynamic Yield - Personalization & customer experience management
SearchSpring - SearchSpring is an eCommerce site search tool.
Optimizely - A/B testing you'll actually use.
Nextopia - eCommerce Site Search & Navigation