1. A distributed open-source database with a flexible data model for documents, graphs, and key-values.

  2. Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.

  3. Meet Neo4j: The graph database platform powering today's mission-critical enterprise applications, including artificial intelligence, fraud detection and recommendations.

  4. MongoDB (from "humongous") is a scalable, high-performance, open source NoSQL database.

    open-source

  5. HTTP + JSON document database with Map Reduce views and peer-based replication

  6. High-performance, distributed memory object caching system

  7. OrientDB - The World's First Distributed Multi-Model NoSQL Database with a Graph Database Engine.

  8. Aerospike is a high-performing NoSQL database supporting high transaction volumes with low latency.