Findability
Algolia
SearchTap.io
ElasticSearch
OpenSearchServer
Xapian
Expertrec
elasticsearch-head
Relevanssi Light
Algolia
Site Search 360
ElasticSearch
Relevanssi
IADB
Google Custom Search Engine
Fork CMS
FindabilityAlgolia - 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.
SearchTap.io - SearchTap is a search technology that can easily integrate with websites and mobile apps to provide an Amazon-like search experience without writing any code. It solves search problems for websites, businesses, mobile apps and enterprise software.
Site Search 360 - Site Search 360 enhances and improves your built-in CMS or product search with autocompletion, semantic search, filters, facets, detailed analytics, and a whole lot of customization options.
ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.
OpenSearchServer - OpenSearchServer is an open source application server allowing development of index-based...
Relevanssi - Relevanssi replaces the standard WordPress search with a better search engine, with lots of features and configurable options.