with Lorelle and Brent VanFossen

File Extensions: What program does this file belong to?

If you dig into your computer’s hard drive innards, the stuff and junk you may have stockpiled all over the hard drive, you may often encounter a file with an extension you do not recognize and want to know “what program does this file belong to?” FILExt – The File Extension Source is an online source that helps search for file extensions to identify which program they belong.

A file name is made up of two sections, the first part that is the actual name of the file, followed by a period or “dot” and then the 3 or 4 letters that make up the file extension.


Some familiar file extensions would be html for HTML web pages, doc and xls for Microsoft Word and Excel files, and txt for text files.

FILExt features several ways of searching for file extensions by name or alphabet list. The file extension might bring up more than one option, so look for other clues that might help you identify the program associated with the file. For example, which directory did you find it in? Did you install one of the programs in the results? If not, it’s probably not that one.

We love helpful resources like this!

One Comment

  • Posted April 17, 2007 at 16:40 | Permalink

    Actually, want you are talking about is the mime-type of the file, but often (due to MS’ lack of flexibility) people think the way to identify the type of a file is by the extension. Want you really want to do is figure out what mime-type it has.

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