Some sites pays you to test apps on smartphones or tablets.
On other apps you can directly take income by displaying advertising.
You will find things for IOS, Android or even other mobile operating systems.
I worked hard to promote them, and last time I wated for my payment that I earned in a month it's about 0.5 $ in ethereum, and they didn't pay me and then when I asked them to pay they just blocked me ! I hope they will unblock me, but I think they are scam bad people !