Apache Solr - Solr is an open source enterprise search server based on Lucene search library, with XML/HTTP and...
Appbase.io - Search stack for building modern apps
ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.
Searchkit - UI components for Elasticsearch
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.
X to Elasticsearch Sync - CLI for importing MongoDB, SQL, CSV, JSON to Elasticsearch