Mcent is the best apps for free recharge. I am using this from many days. They will provide you cash from which you can easily recharge your registered mobile number.
Following procedure you have to do get money from mcent are:
1)Open the apps regularly, then you will get bonus everyday
2)Complete the offer in mcent and they will provide you the money as it is written in the offer.
for example: They will tell you to install cleartip and they will give you guideline how they will provide you money.For installing they will give you certain money.For registering they will provide some part of the money and for using few days they will provide rest money.
Best part about mcent is that it is not vague and they provide money and they will recharge within 24 hours.
If you are a student, then this is the best apps to use for free recharge.