Is the facebook app for i devieces and android free?

[You Know Me]

I want to join a phone company that has free social networking sites and Facebook as one also eBay a twitter sorry ill ask different questions as well. if i use my eBay,twitter and Facebook app will that use normal data or will it use the unlimited. i know i should ask the phone company but I figured other companies do it as well.
Thank you for your answers in advance

[D.B]

Yes the fb app on both devices are free, and they use data in the background and you could potentially go over your data limit if you use them a lot....unless you have sprints unlimited plan for smartphones then you don't have to worry about going over