RethinkDB RethinkDB pushes JSON to your apps in realtime.
Apache Cassandra Distributed database management system
Apache CouchDB Document-oriented NoSQL database.
Riak Distributed NoSQL key-value data store.
Redis Key-value cache and store.
Apache Solr Lucene based search server.
ElasticSearch Lucene based search server.
TokuDB Storage engine for MySQL & MariaDB with compression.
TokuMX MongoDB clone with high performance, compression and ACID.
MongoDB Open source document database.
ArangoDB The multi-model NoSQL databas
Neo4j Graph Database Neo4j is an open-source graph database, implemented in Java.
OrientDB ACID compliant multi-model database with SQL like language.