The File Extensions Database


.PROJ File Extension

  • Developer by: Apple, Inc.
  • Category: Various data Files

What is an .PROJ file?

.PROJ is Apple NeXT Interface Builder project

The proj file extension is related to Interface Builder from Apple.

The proj file contains project. Interface Builder first made its appearance in 1988 as part of NeXTSTEP.

The proj file extension might also be used by other programs for their projects.


How to open:

Use Interface Builder to work with *.proj files.

How to convert:

As far as we know, this .proj file type can't be converted to any other file format. This is usually the case of system, configuration, temporary, or data files containing data exclusive to only one software and used for its own purposes. Also some proprietary or closed file formats cannot be converted to more common file types in order to protect the intellectual property of the developer, which is for example the case of some DRM-protected multimedia files.

How to solve problems with PROJ files

  • Associate the PROJ file extension with the correct application. On :
    Windows: Right click on any PROJ file and then click "Open with" > "Choose another app". Now select another program and check the box "Always use this app to open *.PROJ files". Mac: Right click (or Ctrl-click) the PROJ file, then click "Open with" > "Other...". Then choose another program and check the "Always Open With" box. Linux: Right click on the file, and select "Open with" and choose another program. iPhone: Tap the file. If you do not see an app to open the file, then tap Share "Share" and choose an app. Alternatively, save the file. Then open the Files app Files app. There long-press on the file, then release your finger. You will see a black menu bar. Then tap "Share" and select an app. Android: Tap the Settings icon on your smartphone, then tap on the Apps section. There tap the Options icon in the top right-hand corner of the screen to change the default apps.
  • Update your software that should actually open .PROJ is Apple NeXT Interface Builder project. Because only the current version supports the latest PROJ file format. Search, therefore, e.g. on the Apple, Inc. manufacturer website after an available .PROJ is Apple NeXT Interface Builder project update.
  • To make sure that your PROJ file is not corrupted or virus-infected, get the file again and scan it with antivirus software.