If you don't mind a UK specific API, there is http://postcodes.io http://postcodes.io. No authentication needed, it uses open data which is a plus, it can be d

If you don't mind a UK specific API, there is http://postcodes.io http://postcodes.io. No authentication needed, it uses open data which is a plus, it can be demoed from the home page. It may not be the most interesting for children by itself but you can always hook it up to Google Maps or MapBox. There is also Google's geocoder which can be used without an API key last time I checked and they have pretty good demos. https://developers.google.com/maps/documentation/javascript/examples/geocoding-simple https://developers.google.com/maps/documentation/javascript/...