OrientDB

OrientDB is a deeply scalable document-graph database with support of ACID Transactions, SQL and Native Queries, Asynchronous Commands, Intents, etc. OrientDB can work in schema-less mode, schema-full or a mix of both. Supports advanced features, such as ACID transactions, indexing, fluent and SQL-like queries. OracleDB has native native support for JSON documents.

OrientDB is amazingly fast.

OrientDB can be embedded or work as remote service.