Intelligent search made easy
Ransack is the successor to the MetaSearch gem. It improves and expands upon MetaSearch's functionality, but does not have a 100%-compatible API.
Chewy provides functionality for Elasticsearch index handling, documents import mappings and chainable query DSL
Sunspot is a library providing a powerful, all-ruby API for the Solr search engine. Sunspot manages the configuration of persistent Ruby classes for search and indexing and exposes Solr's most powerful features through a collection of DSLs. Complex search operations can be performed without hand-writing any boolean queries or building Solr parameters by hand.