OrientDB is a 2nd Generation Distributed Graph Database with the flexibility of Documents in one product. It is a unique, true multi-model DBMS equipped to tackle today's big data challenges and offers multi-master replication, sharding as well as more flexibility for modern, complex use cases. Users get all of this with an Open Source commercial friendly Apache 2 license.
OrientDB is incredibly fast (storing 220,000 records per second on common hardware). It supports schema-less, schema-full and schema-mixed modes and includes SQL among its query languages along with a custom SQL based language which reduces the learning curve for those new to OrientDB. If you're new to the world of graph databases and wish to try out OrientDB community, check out our Working with Graphs tutorial.