Is iMessage free over wifi connection?

Hello:)
So I have an iPhone and I really wanna keep iMessage on. So is it free if I'm using wifi? I don't want to be charged extra for the messages. Im Not using the service connection only the wifi connection. Also, is my FaceTime usage going to be charged as well?

Thanks:)

No and still no. It's all free.iMessage and FaceTime are two applications pre installed with iOS. Features controlled by apple.cell providers have no control over this at all. IMessage will also work on 3G. Hope this helps

Yes, iMessage is free on the iPhone as is Facetime. You will not be charged for using iMessage to send messages. However, only users who have iOS 5 or newer will be able to receive your messages. Non iPhone users will not be able to receive your messages. Older iPhone users won't be able to receive your messages either unless they update their iPhone firmware.

Imessage is always free, even over cell towers.

IMessage and FaceTime are always free they don't use any phone minutes or texting, they use data (so as long as you're connected to the WiFi connection you won't be charged for either service.