What is .APP file extension?
Application program (or executable file) that runs under Mac OS X; runs when double-clicked; similar to a .EXE file in Windows.
Because APP files are Mac OS packages, you can right-click (or control-click) an application and select "Show Package Contents" to view the files contained in the package. These include Resources used by the application, executables, property list (.PLIST) files, frameworks, plugins, icons, and other files.
In Windows and Linux systems, it may be possible to view the contents of a Mac OS X application as if it were a folder. A decompression program like WinRAR may also be able to extract files from a Mac OS X application on other operating systems.
NOTE: Files within an application package should not be edited or moved, since changes may prevent the program from running correctly.
You can see a list of software programs here on easyfileopener.org that can open this file type so that you don’t need to search for it on the web. You can then open your file with this extension using a software listed below.