Redis - Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.
Apache Ignite - high-performance, integrated and distributed in-memory platform for computing and transacting on...
MongoDB - MongoDB (from "humongous") is a scalable, high-performance, open source NoSQL database.
memcached - High-performance, distributed memory object caching system
Aerospike - Aerospike is a high-performing NoSQL database supporting high transaction volumes with low latency.
CouchBase - Document-Oriented NoSQL Database