MongoDB is a source-available cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with optional schemas.
PostgreSQL is a powerful, open-source object-relational database system. With more than 30 years of active development, it has a strong reputation for reliability, data integrity, and correctness.
MySQL is a widely used, open-source relational database management system (RDBMS) that enables the efficient delivery of high-performance, read-intensive applications.