The .ASHX extension belongs to ASP.NET web handler file types. These are the intermediate web pages that are requested from the server by a client who is trying to fetch an ASP.NET website.

These .ASHX files also contain references to other webpages. Another popular use of the ASHX file is to send PDF documents over the internet.Upon a file transfer for a PDF file,the end user has to manually change the extension to .PDF to view them in their PDF reader software.Mostly these handler files are used for intermediate data transfer in case of ASP.NET websites from the server.