what will be the best Locations API to fetch the suburbs or postcodes?

I am trying to fill my dropdown with all australian suburbs or postcodes or locations when user tries with search terms. I am using auspost.com.au API but they are not giving me results until I give them 3 chars search terms and no results for "becknham". So kind of stuck at where to look for some good API. Tried hand with Google Places API but its giving me places name. I want the suburb names or postcodes or location names statewise or countrywise any.