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What is an ASMX File?

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Question: What is an ASMX File?

Did you find an ASMX file on your computer and wonder what program should open it? Maybe someone emailed you an ASMX file but you're not sure how to use it. Perhaps you tried to open the ASMX file but Windows told you that it could not open it.

Before you can open an ASMX file (assuming it's even a file format that's intended to be viewed or edited), you'll need to determine what kind of file the .ASMX file extension refers to.

Answer: A file with the ASMX file extension is an ASP.NET Webservices Source file.

Other types of files may also use the ASMX file extension. If you know of any additional file formats that use the .ASMX extension, please let me know so I can update this information.

How To Open an ASMX File

The easiest way to open an ASMX file is to double-click on it and let your PC decide which default application should open the file. If no program opens the ASMX file then you probably don't have an application installed that can view and/or edit ASMX files.

Warning: Take great care when opening executable file formats received via email or downloaded from websites you're not familiar with. See my List of Executable File Extensions for a listing of file extensions to avoid and why.

ASMX files are files used with ASP.NET programming and can be opened with any program that codes in ASP.NET (like Microsoft Visual Studio).

ASMX files are not intended to be viewed or opened by the browser. If you've downloaded an ASMX file and expected it to contain information (like a document or other saved data), it's likely that something is wrong with the website and instead of generating usable information, it provided this server-side file instead. Try renaming the file to the correct extension as a short term fix.

If you know anything else useful about ASMX files, please let me know so I can update this page.

Tip: Use Notepad or another text editor to open the ASMX file. Many files are text-only files meaning no matter the file extension, a text editor may be able to properly display the file's contents. This may or may not be the case with ASMX files but it's worth a try.

If you find that an application on your PC does try to open the ASMX file but it's the wrong application or if you would rather have another installed program open ASMX files, see my How To Change the Default Program for a Specific File Extension guide for making that change in Windows.

How To Convert an ASMX File

There are two main ways to attempt to convert an ASMX file to another file type:

The first option involving opening the ASMX file in its native program is preferable because it's both easier and will probably result in a more accurate file conversion. Of course if you don't have a program that opens ASMX files, a third-party file conversion tool (the second option) could be very useful.

Important: You cannot usually change a file extension to one that your computer recognizes and expect the newly renamed file to be usable. However, in the case of ASMX files, as discussed several paragraphs above, this is exactly what you'll probably have to do in most cases where you download one.

Still Having Problems Opening or Using an ASMX File?

See Get More Help for information about contacting me on social networks or via email, posting on tech support forums, and more. Let me know what kinds of problems you're having with opening or using the ASMX file and I'll see what I can do to help.

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