In android phone, when you format your smart phone then after need some important application install on your mobile. occasionally you don't have enough INTERNET DATA. So you can create setup of your important Apps and Save your Data.
1:- Firstly go to google play site from computer or PC.
2:-Suppose if you want download 'WhatsApp' android setup.
3:Copy the URL link from google play store(as you seen in above picture)
4:Then Open this setup downloading site "Android Setup Downloader Site Here"
5:- Paste the copy link at Red circle (as seen as above picture) then click generate download.
