Android Kit Applications. Mac, Windows or Android are the typical operating systems installed on smart phones which have popular currently. The commonest OS is the android. Many mobile phone manufacturers can install android applications in their gadgets since it is an open source platform. Mobile phones, therefore, have become cheap to manufacture since an OS is already available. Various apps are coming up every day, but the most common ones are the android apps. Files and folders of different types can be carried in an application when it is fully developed. These define its functionalities and resources. An archive that has all the essentials need to be built before one can operate the app on a mobile phone. The archived file become known as android package kit (apk). All the data and files that are required to run an app on a cell phone device are contained in an APK package. The functions and abilities of an application is contained in the source code. The other name for the source code is the classes.index. Manifest file is the other component of the APK. Some of the functions of the component is to provide specifications for permission to the application’s needs, package, it’s flow, signatures, certificates, version codes and SHA-1 Digest. The other component is referred to as libs. Lib is a directory that stores information for the application through jar files or codes. The asset component has a directory that files texts, fonts and audio. The layout for the various pages of the app are determined by a component known as resources. The kit also contains res and META-INF directories. Testing of an application has to be carried out during development. Then an export APK is generated where the ones developing it sign in the app with a coded key. This is done to prove of their authority over the application. The signed APK is then uploaded to Google play store so that users can have access to it. The APK is the one that is downloaded and installed on the phone when one requests the app from play store. Aside from the Google play store, the other platform that offers android applications for free without requiring an account is the APK MIRROR. Applications found in Google play store can be downloaded in the APK MIRROR. It, however, does not require one to have an account. Security measures have been put in place by both APK MIRROR and Google to ensure that only original and trusted apps are made available to customers. The High-security measures include signature authorization and verification of certificates. One advantage that comes with using APK MIRROR is the capacity to access earlier versions of an app.