Is Apple MapKit free?

Excuse me, could you clarify something for me? I was wondering about the pricing structure of Apple's MapKit. Specifically, is it offered free of charge to developers who wish to integrate it into their apps? Or does it come with a licensing fee or some other form of cost? I'm trying to budget for a project and need to know if I should factor in the expense of MapKit into my estimates. Thank you for your help!