This is a quick survey application. Which has now been launched in India as well. You can win Google Play credits by taking this survey. It is created by Google Surveys team. You get rewarded for completing this survey. With this reward you can buy any app from google playstore.
In these very easy ways!
If you want to buy any app from playstore for free then this is the best way. This is an app that gives you revenue by surveying some companies.