App Sharer let you to easy share your apps to your friends or backup, you can share by link of Google play or directly share APK (App's full package).
App Sharer support many method to share your apps, you can share by message, mail, bluetooth, QR-Code etc..
By using the feature to backup APK to SD card, you could backup your app to your SD card.
App Sharer also support share multiple apps at one time, and support instant search, easy to find your apps.

Disclaimer: Before share APK, please make sure you have the redistribution right.