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).<p>The barrier is that the official source of zip code data, <i>National Five-Digit ZIP Code and Post Office Directory</i>, is copyrighted[0], and there is work in extracting the data from it.<p>The nice thing is that US copyright law limits the protection for &quot;facts&quot; [1].  The selection and arrangement of facts can be copyrighted, but not the underlying facts themselves.  So it&#x27;s perfectly legal in the US to take the zip code data and distribute it, just not in the original form from the <i>National Five-Digit ZIP Code and Post Office Directory</i>.<p>As for other countries than the US, it would depend on their local laws.<p>[0] - <a href="http:&#x2F;&#x2F;pe.usps.com&#x2F;Archive&#x2F;HTML&#x2F;DMMArchive0810&#x2F;G013.htm" rel="nofollow">http:&#x2F;&#x2F;pe.usps.com&#x2F;Archive&#x2F;HTML&#x2F;DMMArchive0810&#x2F;G013.htm</a><p>[1] - <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Copyright_law_of_the_United_States#Compilations_of_facts_and_the_sweat_of_the_brow_doctrine" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Copyright_law_of_the_United_St...</a>