Grindabuck is one of the most flexible sites to earn free gift cards. It is possible to earn rewards points by listening to music, watching videos, taking surveys, viewing advertisements, completing micro tasks, downloading paid apps and games, winning contests, and taking advantage of mobile offers.

grindaBuck rewards store page
You can earn 100 grindabucks, a $1 value, just for signing up. Reward points (grindabucks) can be redeemed for gift cards or Bitcoin. Some of the gift card redemption options include Amazon, Walmart, and GameStop.