Cash back rebate services like cashbackforex.com and it’s NFA Member USA sister-site cashbackforexusa.com earn commission for every trade placed by traders they refer to the industry leading brokers they work with. They then pay their clients a cash back rebate on every trade.
They don’t markup the spread or commission, so you get better rates going through them than signing up directly with the broker. That may be hard to believe, but just ask the broker themselves! It’s similar to getting cash back rewards on your credit card.