Yes, Path of Exile is completely free to play. This is the case for both the PC and the console version of PoE. However, there is a PoE store in the game. However, only cosmetic items can be purchased there, which do not give the player an advantage. Thus, PoE does not fall into the "pay-to-win" model. You don't have to spend money in the PoE store either. So, this is optional.