Super Slots is one of the most user-friendly sites I have reviewed and has a massive selection of banking methods to cater to a wide audience. The welcome bonus is generous (250% up toR$1,000) although the rollover requirements are high. I think this is a solid option for any online casino player.
All in all, there are free slots that pay real money, but you will have to be playing at real money online casinos as opposed to social casinos on slot apps, or playing titles in demo mode.