eXist

eXist is an open source database management system and application platform built using XML technology. eXist stores XML data and features an index-based XQuery processing function. eXist is written in Java and provides XQuery and XSLT as its search and application programs but it is compatible with other languages and frameworks. eXist is a schema-less database meaning that it can store "textual or binary data and documents without requiring a database schema". eXist is "fully based upon Open Standards and Open Source making it a future-proof and substainable choice".