ZIP codes can be found at USPS.com, ZIPInfo.com and UnitedStatesZIPCodes.org, as of 2015. All three websites prompt users to enter an address to find the ZIP code.
ZIP codes are found on USPS.com by clicking Look Up a ZIP Code on the home page. On the next page, visitors enter the street address and city, select the state and click Find.
An alternative is ZIPInfo.com, where users can select Click Here for Free ZIP Code Lookup on the home page. Visitors enter the street address, city and state and click Go.
Find a code UnitedZIPCodes.org by entering the street address, city and state and clicking Search on the home page. The nine-digit ZIP code and a regional map of the area are displayed.