OrientDB - OrientDB - The World's First Distributed Multi-Model NoSQL Database with a Graph Database Engine.
Datahike - A durable datalog database adaptable for distribution.
PostgreSQL - PostgreSQL is a powerful, open source object-relational database system.
Matisse - Matisse is a post-relational SQL database.
ArangoDB - A distributed open-source database with a flexible data model for documents, graphs, and key-values.
Valentina Server - Valentina Server is 3 in 1: Valentina DB Server / SQLite Server / Report Server