The .ashx file extension is most commonly used by the ASP.NET HTTP handler that was created by Microsoft. Files that contain the .ashx extension are web pages that are processed by an ASP.NET handler.
When a visitor accesses this type of web page, the handler references another page that produces a specified code. The code is then sent to the visitor's Internet browser. The files that contain the .ashx file extension are very similar in nature to ASPX files.
ASHX files are a common way of implementing an http handler without the need for pre-compiling of the handler code within your files.
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If you have additional information about the ASHX file format or software that uses files with the ASHX suffix, please do get in touch - we would love hearing from you.