XMLHTTP is a set of APIs that can be used by JavaScript, JScript, VBScript and other web browser scripting languages to transfer and manipulate XML data to and from a web server using HTTP, establishing an independent connection channel between Client-Side and Server-Side.

XMLHTTP is an important part of the Ajax web development technique, and it is used by many websites to implement responsive and dynamic web applications. Examples of XMLHTTP applications include Google's Gmail service, Google Suggest dynamic lookup interface, MSN Virtual Earth and MapQuest dynamic map interface.

Besides XML, XMLHTTP can be used to fetch data in other formats, e.g. JSON or even plain text, including data provided by executing back-end database queries.