OrientDB from OrientDB Ltd is a multi-model database with extended property graph database capabilities. The multi-model nature - hybrid document/graph in the first instance - of the product means that it is particularly suitable for graph applications that involve unstructured data.
It is an open source offering although there is an Enterprise Edition (with various support options) available with additional features such as monitoring, auditing, incremental backups, multi-data centres, and so on. Cloud-based options are also available for AWS and Microsoft Azure.
The product is targeted at both operational and hybrid operational/analytic environments and it is also worth commenting that the company has considerable success with third party technology companies (most notably Quest Statistica, Informatica and Diaku [recently acquired by Informatica]) embedding its database into their products.
The Community Edition of OrientDB is available for free download and there is an Enterprise Edition, as mentioned. The company lists a large number of users on its website - many of them major organisations - however, it is unclear whether these are users of the Community Edition or the Enterprise Edition. See http://orientdb.com/customers/.
The company claims that OrientDB was the first multi-model graph database to be launched (in 2009). Originally, it was designed as a hybrid document/graph database, but since then the core (native) engine has been extended to include objects, spatial and key-value elements. The product is ACID compliant and supports strong consistency though eventual consistency is an option. It supports Apache Tinkerpop and, especially, Gremlin. However, more importantly, it uses an extended form of SQL for query processing that leverages MapReduce under the covers. The product can be used in full schema, schema-free or hybrid schema environments and uses sharding for distributing data across a cluster.
In addition to the database itself, there is a native ETL engine that can be used to import and export JSON documents and, moreover, Teleporter (the product name) provides transformation capabilities for mapping from a relational to a graph model. There is also a Studio product that allows viewing and editing of the environment, and there is a JDBC connector to support integration with various (partner) visualisation tools.
The company has recently introduced a Neo4j to OrientDB Importer product, which does what its name suggests. There is also a Spark Connector which enables the use of Spark GraphFrame on top of OrientDB Graphs.
The Enterprise Edition of OrientDB comes in bronze, silver and gold flavours, each offering different levels of service coverage. In addition, the company provides both developer support and online and on-site consulting services. There is a free to use online training video while on-site and online training courses are also available.