Android Kit Applications. Majority of people nowadays have smart phones which are either windows, Mac or Android OS. The most popular is the android. The availability of Android as an open source platform has enabled many mobile manufacturers to install it on their gadgets. The cost of production has, therefore, gown down due to the availability of the free OS. 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. In order for a mobile app to function, an archive with all the necessities is required first. The archived folder is commonly referred to as APK. Runnning an app in a mobile phone requires some special data and files that are found in an android package kit. The functions and abilities of an application is contained in the source code. It is generally referred to as classes.dex. The APK also comprises of the manifest file. Provisions of specifications for permission to the application’s needs, package, it’s flow, signatures, certificates, version codes and SHA-1 Digest are some of the functionalities of the component. Libs is the other vital component for the APK. The element comprises jar files and codes which act as library for the application. Asset is the other element of APK and performs the functions of filing fonts, audios, and texts. The resources component is the element which defines the layout for the various pages of the app. The kit also contains res and META-INF directories. Testing of an application has to be carried out during development. The developers of the app generate an export app where they sign in the application with secret code. The purpose for that is to enhance authenticity. Uploading of the app in to the Google play store is done to allow users download 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. An account is however not required like in the case of Google play. 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. Authorization of signatures and verification of certificates are some of the security measures. One of the features provided by the APK MIRROR is the ability to provide older versions of the app if one is not satisfied with the new one.