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.

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

Google Custom Search - Google Custom Search enables you to create a search engine for your website, your blog, or a collection of websites.

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