In the centre of the town, on larger squares, such as Jelacic Square, at shopping malls like Avenue Mall or Arena Shopping Centre, there is a free WIFI. Just agree to the terms of use, usually there are no passwords, and you will be connected. If you are sitting in cafés or dining out, nearly each of this places has free WIFI, they usually have passwords written on menues or on bills or just simply ask your waiter for it.
And…stay connected ! 🙂

Free WIFI in Zagreb