Sooqr - Sooqr Search provides relevant and innovative site search engine for the website.
SearchBlox - SearchBlox is an out-of-the-box Enterprise Search Solution built on top of Apache Lucene/Solr.
Google Custom Search - Google Custom Search enables you to create a search engine for your website, your blog, or a collection of websites.
Hulbee Enterprise Search - Hulbee Enterprise Search is another powerful site search solution that intelligently retrieves information and documents regardless of their source or location.
Varonis DatAnswers - Varonis DatAnswers is a leading enterprise search and discovery platform that deliver secure and relevant searches for authorized NAS, Windows files servers and share point users.
Datafari - Datafari is a leading open-source enterprise search engine that was released under the Apache License with the multitude of connectors.