is it really free?

Hi! Curious as to what or how a free plan actually is free? Do you give away our data? Do you provide other companies with our information to keep it free? Is any data shared with other companies? Or is it really this good and it's free if that's the only features you need? Do you earn money for each card transaction processed? I'd appreciate honest feedback as I am seriously looking at your service and find it hard to believe all the essentials are free.