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.
ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.
WebshopLogic WP Google Search - Free plugin for integrating Google Custom Search box into your WordPress website without coding.
Xapian - Xapian is an open source probabilistic information retrieval library, released under the GNU...
Advanced Woo Search - Advanced Woo Search - WordPress ajax search plugin for WooCommerce store. Search in product title, description, excerpt, sku, tags, categories, attributes, custom fields, custom taxonomies.
Apache Solr - Solr is an open source enterprise search server based on Lucene search library, with XML/HTTP and...