Telepat.io Cloud - Open source, real time API platform
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.
API Plug - API Plug enables developers to create their own REST API and backend management software from their...
Apache Solr - Solr is an open source enterprise search server based on Lucene search library, with XML/HTTP and...
WrapAPI - Build an API on top of any website
ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.