PostgreSQL

PostgreSQL (https://www.postgresql.org/) is another free and open source database system that is very much in demand. It is actively maintained by a community. One of the unique features of PostgreSQL is the advanced JSON object storage with the capability to index and query within the JSON. This makes it possible to use it as a NoSQL database or in Hybrid mode. It also has enterprise-ready features such as replication, high availability, and so on.