What Is an ASP File?

Most ASP files are web pages that you can edit in a text editor

By
Tim Fisher
Photo of Tim Fisher, Lifewire GM and Writer
Tim Fisher
Senior Vice President & Group General Manager, Tech & Sustainability
  • Emporia State University
Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the SVP and General Manager of Lifewire.
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Updated on November 9, 2022

What to Know

  • Some ASP files are Active Server Page files. Open one with any text editor.
  • Others are Adobe Color Separation Setup files. These are used by Adobe software, like Illustrator and Photoshop.

This article explains what an ASP file is and how to open one on your computer.

What Is an ASP File?

A file with the .ASP file extension is most likely an Active Server Page file, which is an ASP.NET web page provided by a Microsoft IIS server. The server processes scripts within the file and then generates HTML to display the page in the browser.

These files are also called Classic ASP files, and normally use the VBScript language. Newer ASP.NET pages are saved with the ASPX file extension and are often written in C#.

ASP files that open with notepad

A common place where you might see ".ASP" is at the very end of a URL that points to an ASP.NET web page, or when your browser sends you an ASP file by accident instead of the actual file you were trying to download.

Other file formats use this same file extension, like Adobe Color Separation Setup, but that format might be obsolete and irrelevant with newer program versions. These files contain color options (like separation type, ink limit, and color types) that are used when exporting or printing a document.

Some technology terms are abbreviated as ASP, but they're not related to either of the formats on this page. Application Service Provider, Analog Signal Processing, ATM Switch Processor, Addressable Scan Port, Advanced System Platform, and Auto-Speed Port are some examples.

How to Open Downloaded ASP Files

If you got an ASP file when you tried downloading something else (often a PDF), then there's a good chance that the server simply didn't name the file correctly.

For example, maybe you were trying to download a bank statement, and instead of having it open in your PDF viewer, it opens with a text editor or your computer doesn't know how to view it.

In this particular case, the server didn't append ".PDF" to the end of the file name, and instead used ".ASP" even though the actual file format is PDF. The easiest solution here is to just rename the file yourself, by erasing the last three letters after the period and putting in .PDF (e.g., statement.asp to statement.pdf)

This naming scheme isn't how you actually convert one file format to another, but it's completely acceptable here, since the file is truly a PDF but simply wasn't named appropriately. You're just completing the renaming step that the server didn't do itself.

How to Open Other ASP Files

Active Server Page files that end in .ASP are text files, meaning that they are fully readable (and editable) in a text editor like Notepad++, Brackets, or Sublime Text. Some alternative ASP editors include Microsoft Visual Studio and Adobe Dreamweaver.

A URL that ends with .ASP, like the one below, just means that the page is running in the ASP.NET framework. Your web browser does all the work to display it:

  • https://www.w3schools.com/asp/asp_introduction.asp

Since ASP files need to be parsed before being sent to a web browser, opening a local ASP file in a browser will just show you the text version, and won't actually render the HTML page. For that, you'd need to be running Microsoft IIS and open the page as localhost.

You can create ASP files from a blank document by just appending the file extension to the end of the file. This also works for converting HTML to ASP—rename the extension from .HTML to .ASP.

Adobe Color Separation Setup files work with Adobe programs like Acrobat, Illustrator, and Photoshop.

How to Convert ASP Files

Active Server Page files can be converted to other formats, but doing so would mean that the file would stop working the way it was intended to work. This is because the server that gives out the file needs it to be in the proper format in order to display pages correctly.

For example, saving ASP to HTML or PDF would let the file open in a web browser or PDF reader, but would also prevent it from working as an Active Server Page file if it were used on the web server.

If you do need to convert an ASP file, you can use Visual Studio or Dreamweaver. Those programs will let you convert to formats like HTML, ASPX, VBS, ASMX, JS, SRF, and more.

This online ASP to PHP converter can perform that conversion if you need the file to be in the PHP format.

Still Can't Open It?

.ASP closely resembles other extensions that have nothing to do with the formats mentioned on this page, and so won't open with the same programs linked above.

For example, APS files are project files created and used by Greeting Card Studio. The same concept applies to other ones, like ALP.

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