eXist is an open source database management system built on XML (extensible markup language) technology. eXist stores information (data or metadata) encoded in XML. The database is queried using XQuery (XML query language), and follows many other W3C XML standards, including XPath and XSLT.
eXist includes a query editor and debugger. There is a large library of example data, code and applications that can be adapted.
eXist typically runs as a Java web application under Tomcat, and also comes with a desktop application which is useful for uploading documents in batch-mode.