Orient DB is described as 'The Document-Graph database, SQL and Native Queries, asynchronous commands, intents, and much more' and is an app in the Development category. There are more than 10 alternatives to Orient DB for a variety of platforms, including Linux, Windows, Mac, BSD and Online / Web-based. The best alternative is MongoDB, which is free. Other great apps like Orient DB are CouchDB (Free, Open Source), RethinkDB (Free, Open Source), CockroachDB (Free) and ArangoDB (Free, Open Source).
MongoDB is a document database with the scalability and flexibility that you want with the querying and indexing that you need MongoDB stores data in flexible, JSON-like documents, meaning fields can vary from document to document and data structure can be changed over...
Apache CouchDB is a distributed, fault-tolerant and schema-free document-oriented database accessible via a RESTful HTTP / JSON API. It includes incremental map / reduce mechanics for queries and keeps data safe with an append-only datastore.
RethinkDB pushes JSON to your apps in realtime. When your app polls for data, it becomes slow, unscalable, and cumbersome to maintain. RethinkDB is the open-source, scalable database that makes building realtime apps dramatically easier.
Cockroach is a distributed key/value datastore which supports ACID transactional semantics and versioned values as first-class features. The primary design goal is global consistency and survivability, hence the name.
RedisGraph is a property graph database module for Redis. It is the first graph database to use linear algebra on sparse adjacency matrices to implement graph operations, which lets it achieve high performance. It understands OpenCypher queries.