PostgreSQL - PostgreSQL is a powerful, open source object-relational database system.
MySQL - The world's most popular open source database
Amazon Aurora - MySQL and PostgreSQL-compatible relational database built for the cloud. Performance and availability of commercial-grade databases at 1/10th the cost.
SQLite - SQLite Home Page
MongoDB - MongoDB (from "humongous") is a scalable, high-performance NoSQL database.
Microsoft SQL - Microsoft SQL is a best in class relational database management software that facilitates the database server to provide you a primary function to store and retrieve data.