Methods and apparatus implementing systems and techniques for asynchronously loading and accessing structured data. A random access interface can be provided to structured data while that structured data is asynchronously and simultaneously being loaded from a data source. A document, such as an Extensible Markup Language document, can be sequentially parsed and loaded into memory, and a tree data structure interface to the entire document can be provided to a client before the entire document has been fully parsed. In general, in one implementation, the technique includes: parsing structured data in sequence to produce a data object model representing at least a portion of the structured data in a memory, and simultaneously providing, to a client, read and write random access to the structured data through the data object model in the memory as the data object model is being produced.