I was searching for ways that I can use when I was going to travel to Chile. Because I did not have a plan I could use with the EE network that I am on contract with in London.
Then I came across this app.
This app is very cool, because it shows you all the spots near you, in a city where there is Wi-Fi available. It is basically a crowd-sourced app where users who use a Wi-Fi submit its password, and the app makes it available to the other users of the app.
You should have it if you plan to travel without data.
I would not say it is 100% accurate, some of the passwords are outdated, but still highly effective.
My favourite thing about the app is that, it automatically connects to a Wi-Fi if you turn on the location capabilities to run in the background when you are not using the app. I am an iPhone user, so the settings might be a bit different on an android.
I highly recommend it Wi-Fi Map.