OrientDB is an open source NoSQL database management system written in Java. It is a multi-model database, supporting graph, document, key/value, and object models, but the relationships are managed in graph databases with direct connections between records. It supports schema-less, schema-full, and schema-mixed modes. It has a strong security profiling system based on users and roles, and supports querying with Gremlin analog with SQL, extended for graph traversal.