.APPX File Extension
File TypeWindows 8 App Package
What is an APPX file?
App package format introduced with Windows 8; used by developers when packaging and submitting Windows 8 apps (formerly referred to as Metro Style apps) for sale on the Windows Store.
APPX files can be packaged with Visual Studio 2012, which provides support for developing Windows 8 apps. Use the Create App Packages wizard by choosingin Visual Studio or in Visual Studio Express.
APPX files can be included within .APPXUPLOAD files. Both file types can be used as a submission format to the Windows Store, but APPXUPLOAD files contain additional information that allows debugging information to be sent back to the developer for app crashes.
NOTE: APPX files have a 2GB maximum file size.