Mobile Apps development | File Extensions

One of the principle challenges for Mobile Apps development has been distribution of the application. Traditional computer applications have relied on clunky installers called wizards to sort out and set up the components of a program, but this paradigm does not work well across multiple mobile platforms. Now that we have learned the basics of Mobile App Testing, let’s see different file extensions across multiple mobile OS.

Mobile Apps development – file extensions

.IPA file – Apple’s iOS or iPhone OS

An .ipa file is an iOS application archive file which stores an iOS app. Each .ipa file includes a binary for the ARM architecture and can only be installed on an iOS-device. Files with the .ipa extension can be uncompressed by changing the extension to .zip and unzipping. iTunes can be used to install their contents on a device, provided the included files are signed.

Most .ipa files cannot be installed on the iPhone Simulator because they do not contain a binary for the x86 architecture. To run applications on the simulator, original project files which can be opened using the Xcode SDK are required. However, some .ipa files can be opened on the simulator by extracting and copying over the .app file found in the Payload folder.

IPA iOS File Extension Structure

An IPA has a built-in structure for iTunes and App Store:

  • /Payload/ — contains all the app data
  • /Payload/
  • /iTunesArtwork — a 512×512 pixel PNG image, containing the app’s icon for showing in iTunes and the App Store app on the iPad
  • /iTunesArtwork@2x
  • /iTunesMetadata.plist — contains various bits of information, ranging from the developer’s name and ID, the bundle identifier, copyright information, genre, the name of the app, release date, purchase date, etc.
  • /WatchKitSupport/WK

The extension has no official definition, but is commonly called “iPhone Application Archive” or “iOS App Store Package” by the iOS community.

.APK file – Google’s Android

Android application package (APK) is the package file format used by the Google’s Android OS for distribution and installation of Mobile Apps and middleware. APK files are a type of archive file, specifically in zip format packages based on the JAR file format, with .apk as the filename extension. The MIME type associated with APK files is application/

Mobile Apps development – To make an APK file, a program for Android is first compiled, and then all of its parts are packaged into one file. An APK file contains all program code (such as .dex files), resources, assets, certificates, and manifest file. As is the case with many file formats, APK files can have any name needed, provided that the file name ends in “.apk”. APK files can be installed on Android powered devices just like installing software on PC.

Package contents

  • META-INF directory:

           MANIFEST.MF: the Manifest file

           CERT.RSA: The certificate of the application

           CERT.SF: The list of resources and SHA-1 digest of the corresponding lines in the MANIFEST.MF file

Android APK Structure

  • lib: the directory containing the compiled code that is specific to a software layer of a processor, the directory is split into more directories within it.
  • armeabi: compiled code for all ARM based processors only
  • armeabi-v7a: compiled code for all ARMv7 and above based processors only
  • arm64-v8a: compiled code for all ARMv8 arm64 and above based processors only
  • x86: compiled code for x86 processors only
  • x86_64: compiled code for x86_64 processors only
  • mips: compiled code for MIPS processors only
  • res: the directory containing resources not compiled into resources.arsc
  • assets: a directory containing applications assets, which can be retrieved by AssetManager
  • xml: An additional Android manifest file, describing the name, version, access rights, referenced library files for the application.
  • dex: The classes compiled in the dex file format understandable by the Dalvik virtual machine
  • arsc: a file containing precompiled resources, such as binary XML for example

.Appx file – Windows Mobile 10

Mobile Apps development file format introduced in Microsoft Windows 8 and Windows Phone 8.1 operating systems. Files with an “APPX” extension are basically an application package ready for distribution and installation. The AppX approach is particularly effective for distributing applications suited for multiple devices, including PCs, tablets and smartphones.

APPX & XAP Windows Mobile File Extension

.XAP file – Windows Phone

XAP is the file format used to distribute and install application software and middleware onto Microsoft’s Windows Phone 7/8/8.1/10 operating system, and is the file format for Silverlight applications. Beginning with Windows Phone 8.1, XAP was replaced by APPX as the file format used to install apps on the Windows Phone platform, a move which was done by Microsoft in order to unify the app development platforms for Windows Store apps and Windows Phone apps. The MIME type associated with XAP files is application/x-silverlight-app. An XAP file is a ZIP archive that usually contains the AppManifest.xaml & DLLs required files.

These are the App file extensions for top 3 Mobile operating system. Below is the complete list of File extensions related to mobile phones and other electronic devices (firmware, mobile application packages etc.)…

  • apk – Google Android application package
  • vcf – vCard file
  • asec – Google Android encrypted application package file
  • nomedia – Google Android OS system file
  • crypt8 – WhatsApp Messenger message database file
  • crypt – WhatsApp Messenger encrypted message database backup file
  • obb – Google Android opaque binary blob file
  • pkpass – Apple Passbook pass file
  • bbb – BlackBerry backup (post 2012) file
  • crypt7 – WhatsApp Messenger encrypted message database backup file
  • snb – S Note note (old version)
  • rem – BlackBerry encrypted data file
  • spd – S Note note (new version)
  • kdz – LG firmware archive file
  • vmsg – Versit message format
  • ipa – Apple iOS application file
  • ftf – Sony Ericsson Xperia Android firmware file
  • sbf – Google Android mobile phone backup file
  • xap – Microsoft Windows Phone and Microsoft Silverlight application package file
  • lqm – LG G3 Note text note
  • ipsw – iPhone, iPad or iPod Touch iOS software firmware update file
  • nbu – Nokia PC Suite 6.82+ backup file
  • sin – Xperia system loader
  • npf – Samsung PC Studio phone book backup file
  • bugsense – BugSense file
  • mobileconfig – Apple iPhone mobile configuration profile
  • mms – Multimedia Messaging Service message file
  • tpk – Tizen application package
  • arsc – Dalvik Virtual Machine resource pack
  • nbf – Nokia phone side backup file
  • hbk – HTC SMS backup
  • ithmb – Apple iPhone, iPad, iPod thumbnail image file
  • xapk – Google Android XAPK application package
  • vcard – vCard file
  • ipd – BlackBerry backup (pre 2012)
  • sisx – Symbian OS program installation executable file
  • ldwf – Android related file
  • aba – Palm Address Book archive file
  • mcusw – Nokia mobile phones with Symbian firmware file
  • thm – Sony Ericsson mobile phone theme file
  • fpsx – Symbian firmware update
  • aia – App Inventor project file
  • pit – Samsung firmware file
  • sis – Symbian installation file
  • nth – Nokia Series 40 and 60 theme file
  • pbb – Mobile phonebook file
  • mbn – Sony Ericsson mainware file
  • rsc – Resource file
  • sup – Apple iOS file
  • usv – LG Xenon mobile phone contact list
  • nfb – Nokia PC Suite phone backup file
  • nbh – HTC ROM update utility ROM image file
  • enc – Media Safe encrypted data file
  • oap – Samsung bada signed installation package file
  • mybible – Bible database module
  • wcxf – WorldCard exchange file
  • mddata – Apple iPhone backup data file
  • mswallet – Microsoft Wallet item package file
  • min – Minute Maker file
  • des-se – Sony Ericsson XPERIA X10 file
  • cab – Installation File For Windows Mobile
  • dm – Nokia Ovi Store protected program file
  • ppv – Microsoft Pocket PowerPoint presentation
  • nar – Nokia Smart Cam archive
  • mdbackup – Apple iPhone backup file
  • nfc – Nokia PC Suite phone backup file
  • gkp – GameKeyboard file
  • n3a – Nokia 3D screensaver
  • cdb – Symbian OS contact database file
  • vsm – Blackberry data file
  • s7s – Sony Ericsson S700i Phone firmware data file
  • mxmf – Mobile XMF format file
  • migitallock – Migital encrypted file
  • pme – Plazmic Media Engine File
  • 1sp – Microsoft OneNote Mobile document file
  • Smi – Siemens mobile phone inbox SMS file
  • nomedia_128x96 – Google Android OS system file
  • twk – TweakS file
  • shx – Motorola RAZR flash file
  • slt – Gallery Lock hidden media thumbnail file
  • provisionprofile – iOS Provision profile
  • bar – Brew MP binary application resource file
  • bm3 – Sony Ericsson backup file
  • xmpp – Extensible Messaging and Presence Protocol file
  • iby – Symbian ROM Image Component Include file
  • pxo – LG Vu system file
  • aeg – Netmino file
  • ifaith – iFaith file
  • cuidBaidu.cuid file
  • dict – Sunnysoft InterWrite file
  • pdas – PDAStore store file





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