There is no cost to use the Wunder app.
There is a ₹10 / ₱10 transaction fee on Wallet paid rides. However when you take a Wallet paid ride, Wunder rewards you with ₹20 / ₱20 cashback. But please note that cashback is transferred up to 48 hours after the ride is paid. There is no transaction fee on cash rides but also no cashback!