A system and related techniques and data structures present a Web based or other client application or service with a relational node structure to access, store and manipulate XML-based or XML-compliant data. Unlike unmodified XML information for instance stored in document object model (DOM) format, the inventive platform may load a relational node structure encapsulating XML-compliant information in an organized structure having pointers to next peer, parent, child and other links to related or unrelated information. Searching, querying and other operations may therefore be made more efficient since an entire tree structure need not be exhaustively traversed to locate desired data, but instead sorted via those relational linkages. Client applications such as Web browsing, email, contacts managers, calendars and others may therefore operate on XML or XML-compliant data without the loading or performance disadvantages which conventional XML platforms may incur. The data populating the relational node structure may be obtained from XML or structured sources, and for instance be loaded from storage in response to a query generated via the query engine.