It really depends on how you want to do it. If you use Socket.IO, you do have to have your own server running somewhere else, a good free one is Heroku. Pusher is nice if you know what you are trying to do, know your limits, and how to do it. While Socket.IO allows more flexibility if you need to do something crazy, Pusher is great if you're just doing standard real-time data transfer because there is minimal setup. The only other thing about Pusher is that it is not entirely free, so if you know the pricing, know how much you are going to use, and are willing, you could easily use Pusher.