I frequently get questions like this from Mac users:

My friend asked me to download a file named “naib.exe”, but I can’t open it on my Mac. How can I open this file?

From a person who only uses Mac computers and iPads, this is a very reasonable question.

The quick, short answer is, “By itself, the Mac can’t open this file.”

The longer, more positive answer requires a little background.

File Extensions

Both PC and Mac computers use three- or four-letter extensions on file names—the portion of the name after the period—to determine which application can open a file.

You may have noticed that files with extensions “.jpg” or “.jpeg” are opened by the Preview app on the Mac. Those files are images or photos.

Similarly, you may have noticed that files with extensions “.docx” or “.doc” are opened on the Mac by Microsoft Word or TextEdit. Those files are word processing documents.

What you may not have noticed is that Mac applications themselves have an “.app” extension. (See figure 1.)

exe on Mac

When you double click on a file with the “.app” extension on a Mac, the macOS® launches that application. In other words, opening a file with an “.app” extension is really launching that application; the macOS itself opens that file.

With this background, it is understandable that the Mac by itself can’t open an “.exe” file because the .exe extension means that the file is a Windows application. The Windows operating system is needed to open an “.exe” file.

Enter Parallels Desktop

When you have Parallels Desktop and a Windows virtual machine (VM) on your Mac, everything just works when you double click on an “.exe” file. It feels a little bit like magic.

Underneath, here is how the magic works: Parallels Desktop tells the Mac that it can open “.exe” files. So when you double click on that “.exe” file, the macOS® launches Parallels Desktop. This is just like when you double click on a “.jpg” file and the macOS launches Preview, or when you double click on a “.docx” file and the macOS launches Microsoft Word.

When Parallels Desktop is launched because you clicked on an “.exe” file, Parallels Desktop boots your Windows VM and tells Windows that you want this “.exe” file opened. Windows then launches the application for that “.exe” file.

While the quick, short answer to the question at the beginning of this blog post still is, “By itself, the Mac can’t open this file”… 

The longer, more positive answer is, “This is a Windows file, so you need Windows to open it. The easiest way to get Windows on your Mac is to get Parallels Desktop and a Windows VM.”

Oh yeah, and if you have Boot Camp® on your Mac, you still won’t be able to double click on that “.exe” file and have it open. The short answer to “Why not?” is because the macOS and Boot Camp can’t talk to each other. The long answer will be the subject of a future blog post.