Redis - Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.
MarkLogic - Schema-agnostic Enterprise NoSQL database technology, coupled w/ powerful search & flexible application services
Cloudtrek - We at cloudtrek help companies quickly deploy private cloud solutions preserving their need for greater control, predictable costs, and ease of use.
BaseX - BaseX is a very light-weight, high-performance and scalable XML Database engine and XPath/XQuery...
Riak - A distributed, decentralized data storage system
Apache Xerces - Advanced XML parser, including support for XML Schema, DOM Level 2, and SAX.