ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.

Apache Solr - Solr is an open source enterprise search server based on Lucene search library, with XML/HTTP and...

Xapian - Xapian is an open source probabilistic information retrieval library, released under the GNU...

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.

ItemsAPI - ItemsAPI is open source search API for creating mobile and web application

Sphinx (search engine) - Sphinx is a fulltext FLOSS search engine that provides text search functionality to client applications. Sphinx (search engine) - WikiMili, The Free Encyclopedia - WikiMili, The Free Encyclopedia