The US is full of zip codes regulated by the USPS. These can pose a confusing mess to organize manually.
The free Zip Code API is way simpler and it makes pulling zip codes a breeze. At the moment it only works for the United States but it could easily expand worldwide given enough traction.
One reason you might use this API is to pull related zip codes from a surrounding area. This could be used for a job search website or a housing/real estate web app.
