WhatsOpen 3.0

What's Open is a system utility that lets determine what app is running a file.
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What's Open is a system utility that lets you determine which app is running a file. While using Mac, you probably noticed an error window that states that you can't delete a file because it is open or active. I get that error all the time, and it is often hard to find the application that is running that file. With What's Open, all you need to do is drag the file in question to the app window and it will tell you what application is running it. Some extra information shown includes the user account that is running the file, the file size, CPU time, path and process state. With What's Open not only can you see what app is running a file, but you can also take action. From the toolbar at the top of the screen, you can kill the application. From here, you can also select any volume and force eject it. This is another annoyance I face frequently; not being able to eject a volume because a file is open inside of it.

In my testing of this app, I played an MP3 file on iTunes and then dragged it onto the application. What's Open correctly reported that the file was opened in iTunes, and I was able to kill iTunes from What's Open. iTunes promptly stopped playing the song and then returned an error and quit, which is exactly what I was expecting the app to do.

In short, What's Open is a very useful tool that works quite well at determining what applications are holding your files captive.

José Fernández
Editor rating:

Review summary


  • It works well
  • It is easy to use


  • None
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