If not that - is there any online data source that one can download and get required regions for addresses per country?
I don't need to know how to format an address, which is what everyone seems to think I should want, I need to know what fields will be required in a particular country to make the user inputs.
Do you want to add and remove fields from the webpage according to the country?
I think the general recommendation is to let the user input whatever sting s/he wants, because it's impossible to know the weird formats of each part of the world. (In some tiny towns, "name" + "town" + "province" + "country" is enough. Bonus point for "zip". Street name? There are no streets, homes are just on the side of the main road, on in a secondary road that is only an unnamed dirt strip.)