Retrieving a fully qualified street address from ZIP / postal code

Question

I have a form in which my users need to enter the following location data:

1. Full address line (street address, apartment, suite, unit, building, floor)
2. House number
3. City
4. State / province / region
5. ZIP / Postal code
6. Country

To simplify the completion of this form, I would like to automatically fill in the fully qualified address (addrses line, city, state province etc) by letting the user only enter his country, zip code and house number.

Is it correct that these 3 items are sufficient to lookup the address in the United States? Or is less or more information necessary? And is the answer to this question different for every country? Moreover, is there a service, API, or library that can be utilized for this purpose (e.g. Google Maps or OpenStreetMap)?

Answer 1

Great questions!

Is it correct that these 3 items are sufficient to look up the address in the United States?

No. Unfortunately these three will get you down to ~hundreds of possible addresses in the US.

Is the answer to this question different for every country?

Yes! The postal systems from country to country vary greatly and you're users in them will have different expectations about what they expect to supply - Brits don't expect to have to enter a full address for example.

With the UK, Canada and Australia you can usually get to a single address from the house number and postcode. BUT, you can not guarantee this. There may be sub-premise information or business information which requires a bit of interaction with the user to check you have right address.

Some countries, such as France, do not have complete premise number coverage. With these you can take the premise number & postcode but depending upon the town you have to alter your behavior to either trust and accept the input or prompt them for a correction.

Another important consideration when planning your workflow is the need to allow for people who perhaps do not know their postcode / zip. It does not happen often but sometimes people have just moved, or occasionally a properties postcode/zip changes so it is important to be flexible in the information you need.

Is there a service, API, or library that can be utilized for this purpose?

Yes - there are several solutions around that offer the ability to capture global addresses. Experian Data Quality (my company) offer a hosted or on premise solution that allows for this.

Try it out here - on the right hand side under the "Do you want to know more?" you can switch countries, the prompt updates and the interaction occurs if needed.

Answer 2

I can only answer about US addresses (I work at SmartyStreets), but the answer is no, that won't work.

Kudos for your desires to improve the user experience. Unfortunately, I would not recommend trying this, and here's why:

A US ZIP code, in its entirety, is actually 11 digits long (12 with the check digit):

• The first three digits are the SCF (Sectional Center Facility), kind of like a region code
• The first five digits are your typical 5-digit ZIP code that specifies a set of carrier routes
• The next 4 digits are more precise, often narrowing down an address to block-level.
• The next 2 digits are seldom used except in barcodes, but they indicate the delivery point. In theory, this would specify a particular house, apartment, or mailbox, but in reality, sometimes the 11-digit code is ambiguous (common in large complexes, street blocks, or PO facilities). It's typical for the delivery point to correlate to the house or apartment number, but not always.

So in your situation:

• Knowing the country narrows down the possibilities to just 350,000,000+ addresses
• Knowing the 5-digit ZIP code narrows it down to somewhere around 10,000+ addresses (important note: not everyone knows the 5-digit ZIP code, and they change. What's more, is that they may not be sure whether to enter their PO box ZIP code or their house ZIP code. And what if their house doesn't receive mail? Or what if they're in the military and their 5-digit ZIP is in flux?)
• Knowing the house number may narrow down the address candidates to anywhere from 1-1000. It depends how "big" the ZIP code is. (But ZIP codes are not polygons).

So no, it is not sufficient to know these three parts of the address. The country is practically worthless at that point, and the ZIP code is locality/city-specific at best. The house number might appear dozens, if not hundreds, of times in a ZIP code. (I grew up in the boonies where our house number was unique, but that's rare.)

And yes, the answer to this question varies country to country, but this reasoning holds true for most developed countries. Less developed countries don't have such organization to their postal system.

Is there a service that can do this? Not if you don't want your users to scroll through dozens or hundreds of results. If they have to look through more than just a couple, you're better off just asking them to type their full address.

I answered a very similar question just the other day. You might find it useful.

So now that I've rained doomsday on your idea, how about an alternative? Of course I'm partial to SmartyStreets' autocomplete, which suggests addresses, geo-located close to the user, as they're typing. I should mention that it's free. It doesn't actually verify the address until the user is finished or has chosen one of the suggestions, but it does reduce keystrokes.

Further on this UX vein, I'd recommend putting country as the first field of your address form. This way, you can alter the form's format based on the country they choose. If you use a service like LiveAddress, you can have the user type their address in a format comfortable to them in a single field, rather than across multiple text boxes in your arbitrary order, since LiveAddress can parse their input.

Answer 3

You could easily achieve this by using the google maps reverse geocoding api. Heres a link to its documentation. link

Answer 4

I don't know of any country where there is a one-to-one mapping between a post code and a street address. Except Singapore. Postal Codes in SG In that particular case you can use the post code to fill in the remaining fields, in any other case you can derive the city name and the street address, but not likely the House number.

Example 1: (derive full street address from post code)

https://geocode.xyz/339696?geoit=xml

<geodata>
<latt>1.32035</latt>
<longt>103.87430</longt>
<elevation/>
<standard>
<stnumber>88</stnumber>
<addresst>88 GEYLANG BAHRU</addresst>
<postal>339696</postal>
<city>Singapore</city>
<prov>SG</prov>
<countryname>Singapore</countryname>
<confidence>0.5</confidence>
</standard>
</geodata>

Example 2: (Get most common street address, and other variations of city name)

https://geocode.xyz/27777?region=DE&geoit=xml

<geodata>
<latt>53.06060</latt>
<longt>8.58388</longt>
<elevation/>
<standard>
<stnumber>20</stnumber>
<addresst>20 Bokenbusch</addresst>
<postal>27777</postal>
<city>Ganderlesee</city>
<prov>DE</prov>
<countryname>Germany</countryname>
<confidence>0.5</confidence>
</standard>
<alt>
<loc>
<city>Ganderkesee</city>
<latt>53.06868</latt>
<longt>8.57437</longt>
<cc>951</cc>
</loc>
<loc>
<city>Bremen</city>
<latt>53.07675</latt>
<longt>8.57559</longt>
<cc>172</cc>
</loc>
<loc>
<city>Schierbrok</city>
<latt>53.08639</latt>
<longt>8.58037</longt>
<cc>166</cc>
</loc>

The number in "cc" indicates how many street addresses in that city share the given post code.

Good luck!