Infinispan
An open-source in-memory data grid that stores and distributes key/value data across elastically scalable clusters for high availability and fault tolerance.
Infinispan is an open-source in-memory database offering flexible deployment options for storing, managing and processing data. It provides a key/value store that can hold data of any kind, from Java objects to plain text, and distributes that data across elastically scalable clusters so it stays available and tolerant of node failure whether it is used as a volatile cache or as a persistent data store.
The project's documentation includes a five-minute getting-started guide and a set of simple tutorials for newcomers.
Infinispan is written in Java and released under the Apache-2.0 license.