XML and JSON have become the dominant formats for exchanging data on the Internet, and applications frequently need to send and receive data in many different JSON-based or XML-based formats. For XML data, a query language like XQuery can be used to query data, create or update data, transform it from one format to another, or route data. Adding JSON support to XQuery allows it to perform these tasks for both XML and JSON, combining data from multiple sources as needed. In addition, JSON support gives XQuery a lightweight, simple, and useful data structure that can often simplify queries.

JSONiq is a query language for JSON, based on XQuery. It is designed to allow an existing XQuery processor to be rewritten to support JSON with moderate effort. One profile of JSONiq removes everything directly related to XML, adding JSON constructors and navigation. Another profile of JSONiq includes the full XQuery language, with added JSON support, allowing queries to consume or produce JSON, XML, or HTML.