US zip codes are authorized and assigned by the USPS, so by definition they are proprietary. However, the data itself (once it is obtained) is freely redistrib

US zip codes are authorized and assigned by the USPS, so by definition they are proprietary. However, the data itself (once it is obtained) is freely redistributable (in raw form). The barrier is that the official source of zip code data, National Five-Digit ZIP Code and Post Office Directory, is copyrighted[0], and there is work in extracting the data from it. The nice thing is that US copyright law limits the protection for "facts" [1]. The selection and arrangement of facts can be copyrighted, but not the underlying facts themselves. So it's perfectly legal in the US to take the zip code data and distribute it, just not in the original form from the National Five-Digit ZIP Code and Post Office Directory. As for other countries than the US, it would depend on their local laws. [0] - http://pe.usps.com/Archive/HTML/DMMArchive0810/G013.htm http://pe.usps.com/Archive/HTML/DMMArchive0810/G013.htm [1] - https://en.wikipedia.org/wiki/Copyright_law_of_the_United_States#Compilations_of_facts_and_the_sweat_of_the_brow_doctrine https://en.wikipedia.org/wiki/Copyright_law_of_the_United_St...