Redis
Redis is an open source (BSD licensed), in-memory data structure store, used as a database, cache and message broker. source: redis.io Supported Versions Redis 4.0.2 on Ubuntu 16.04
MySQL
Many of the world’s largest and fastest-growing organizations including Facebook, Google, Adobe, Alcatel Lucent and Zappos rely on MySQL to save time and money powering their high-volume Web sites, business-critical systems and packaged software. source: mysql.com Supported Versions MySQL 5.7.20 on Ubuntu 16.04
Cassandra
The Apache Cassandra database is the right choice when you need scalability and high availability without compromising performance. source: cassandra.apache.org Supported Versions Cassandra 3.11 on Ubuntu 16.04
MongoDB
MongoDB is a document database with the scalability and flexibility that you want with the querying and indexing that you need. source: mongodb.com Supported Versions MongoDB 3.2.17 on Ubuntu 16.04
CouchDB
Apache CouchDB™ lets you access your data where you need it by defining the Couch Replication Protocol that is implemented by a variety of projects and products that span every imaginable computing environment from globally distributed server-clusters, over mobile phones to web browsers. source: couchdb.apache.org Supported Versions CouchDB 1.6.1 on Ubuntu 16.04