This article explains what an ASMX file is and how to open or convert one. We'll also look at what to do if you've accidentally downloaded one.
Create a custom ASP NET (ASMX) web service in on-premises SharePoint
An abbreviation for Active Server Method File. A file with the file extension ASMX is an ASP.NET Web service file.
Unlike ASP.NET web pages, which use the .ASPX file extension, ASMX files function as a service without a graphical user interface. Instead, they are used to move data and perform other actions behind the scenes.
These files are used in ASP.NET programming and can be opened with any program that codes in ASP.NET, such as Microsoft's Visual Studio.
