PostgreSQL - PostgreSQL is a powerful, open source object-relational database system.
Microsoft Office Access - Access is now much more than a way to create desktop databases. It’s an easy-to-use tool for quickly creating browser-based database applications.
MySQL - The world's most popular open source database
LiveCode Platform - It is Both Under the GPL and it is also Proprietary if using the GPL version the software you make...
SQLite - SQLite Home Page
Redis - Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.