Apache Solr - Solr is an open source enterprise search server based on Lucene search library, with XML/HTTP and...
Decisiv Search - Decisiv is an enterprise search solution enabling users to search multiple repositories at once to access documents, projects etc.
ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.
Constellio - Automate secure information sharing
Mindbreeze Inspire - InSpire is a high-performance enterprise search product and big data solution to use out of the package for all of a company's data sources.
Coveo - Enterprise search technology for better customer support, customer self-service, and knowledge management in the digital workplace.