Address Verification


By 31 March 2024April 14th, 2024No Comments
zip code validation

ZIP Code API - Validate US & USPS Zip Codes with API

What is a ZIP Code API?

A ZIP code API is an application programming interface service that provides all data related to ZIP Code such as ZIP+4, Geolocation data (latitude, longitude coordinates), City, State, Country and other metadata associated with the ZIP code.

Today developers are well on their way to optimizing business operations thanks to the age-old ZIP code. We now have access to advanced ZIP code APIs that have revolutionized various business operations, especially marketing.

Advanced ZIP code API typically comes with additional capabilities like address autocomplete, which can help optimize your business operations significantly. It is becoming increasingly evident that ZIP code API has become a necessity for businesses today.

PostGrid's address verification API provides all ZIP Code metadata with its API.

Read more about Geocoding API

zip code validation

What is Zip Code API?

The ZIP code API, also popularly known as ZIP code lookup API, is a tool or system that enables your business to streamline its communication with its customers. Although such forms of communications majorly employ direct mail as their preferred medium, it also streamlines the communication between a business's internal technical system. Furthermore, the accuracy of the data used for communications and the business's internal operations is enhanced by cross-checking it with reliable sources like USPS's official address database.

Access Update Authorative Zip Code Address Database

It is not necessary that ZIP code API uses the official address database of USPS for validating or accessing an address. Depending on your unique requirements, you can use whichever database that works best for you. This includes databases maintained by financial services providers, global retailers, fraud detection companies, and more. So as long as you have an authoritative and reliable address database for your ZIP code API, you need not worry about how accurate or efficient it can be. That being said, USPS is the more popular choice as it holds the country's largest address database.

Why Use an Advanced Zip Code API Validator?

All advanced ZIP code APIs use the official address database of USPS because they have the most extensive collection of address data in the US. The USPS has the most authoritative address database in the country, and they keep a well-managed record of all the addresses and update address changes regularly. Furthermore, there are advanced ZIP code APIs like PostGrid that are equipped with advanced capabilities and features that enable them to streamline numerous business operations effectively.

Validate US & USPS ZIP Code using API

As the name suggests, the US ZIP code API is nothing but a ZIP code API that is specifically made for businesses inside the US. As we have mentioned before, most businesses tend to use a ZIP code API that can access and validate addresses and ZIP codes against the country's official address database maintained by USPS. The ZIP code APIs, including the US-based ones, work essentially the same. They take input from the user and check it against an authoritative database to validate an address or ZIP code.

One thing that you should keep in mind is that the US ZIP code API you use cannot provide you with a ZIP code or have it validated. You will be required to provide sufficient information that will enable the ZIP code API to find the relevant match inside the USPS database. Most companies often use US ZIP code APIs to validate addresses for optimizing their direct mail operations. But, advanced ZIP code APIs like PostGrid also allow advanced features like address autocomplete API, which enables you to maintain a superior quality database for your business right from the point of data collection.

Benefits of Using A Zip Code API

There are numerous advantages of using the ZIP code API for businesses. We have already mentioned a few of them along the way. To get the most out of ZIP code APIs, you need to make sure that you use an advanced version of it rather than a dedicated ZIP code API with limited capabilities. A more advanced ZIP code API gives you access to superior functionalities. Below we discuss some of the major benefits you can get from an advanced ZIP code API.

  • Address correction
  • Address validation
  • Address standardization
  • Lookup unknown ZIP codes
  • Address autocomplete
  • Geocoding capabilities

ZIP Code APIs: Functions & Applications

ZIP Code lookup

A ZIP code lookup is one of the primary functions expected from a ZIP code API. ZIP code lookup is an important part of many businesses and more eCommerce businesses. Although there are dedicated ZIP code lookup APIs available in the market, most businesses tend to go for a more advanced solution that also allows ZIP code lookups. For example, PostGrid has an address autocomplete feature which can be used for ZIP code lookups. An advanced API like PostGrid is capable of returning a full ZIP+4 code of a given address.

Address Standardization

Advanced ZIP code APIs are well capable of conducting an address standardization process. The process is used to standardize addresses to align with the standards specified by the USPS. And if you are sending your mail to a foreign country, then the addresses must align with the postal format specified by that country. Advanced ZIP code APIs are usually equipped to validate addresses entirely and not just the ZIP codes. Such zip code verification web services will carry out address parsing and standardization as part of their address verification process.

Address Autocomplete

The address autocomplete is advanced functionality that you can implement for your business. Implementing an autocomplete feature on our website or landing page has the potential to boost your conversions by making the overall experience convenient for your target audience. As we have mentioned before, you need not find a dedicated API for this as advanced API systems like PostGrid already come equipped with this functionality in the ZIP code API.

Address auto-complete feature can even be an effective alternative for ZIP code to state API, which uses ZIP code to determine the state to which it belongs. Furthermore, the address autocomplete feature ensures that you can clean, real, and deliverable addresses that can be used for various business operations especially, marketing. It is also worth noting that address autocomplete lowers the risk of cart abandonment because the user spends less time filling an order form with their details.

Can You Get Worldwide Postal Code Data with Zip Code API?

The short answer to this question is yes; you can get worldwide postal code data with the help of a ZIP code API. However, it is not the case for all ZIP code APIs, as there are many ZIP code APIs that focus solely on addresses inside the US. Therefore, you need to first analyze your business and its requirements before selecting a ZIP code API for your business. Ensure that the API provider you choose can get you the postal code for every country you are likely to interact with. Furthermore, you can also check whether they have a city lookup by zip code API for optimizing your different business operations.

PostGrid ZIP Code API: A Smarter Way to Validate Zip Codes

We have already made it clear that using a dedicated ZIP code API that can only lookup ZIP codes is an outdated way to go about things in your business. PostGrid ZIP code API offers an advanced solution to businesses that not only enables them to determine ZIP codes but do much more. An advanced system like PostGrid that comes with CASS certification enables you to verify addresses with the click of a few buttons. With PostGrid, you can get access to not just the ZIP code but the whole address in the USPS database. Furthermore, attractive features like the address autocomplete feature allow you to serve your customers better and enhance their convenience while interacting with your business online.

PostGrid – The Best ZIP Code API for Businesses

Businesses today need to keep up with the ever-growing demands of their customers, and using an advanced ZIP code API like PostGrid is one of the ways to do it. PostGrid API is one of the leading ZIP code APIs in the market today, which comes with lots of attractive features, including address autocomplete. With PostGrid API, not only can you make business operations convenient for you and your customers. Furthermore, PostGrid also enables businesses to keep clean and quality data of their customers and potential customers, which can be pivotal for the growth of your business.

What Are The Tools You Can Use For ZIP Code Validation?

There are several tools available that let you verify zip codes with USPS address databases. However, businesses often send out bulk mail. You can even find free tools available that you can use for ZIP code verification API.

USPS Postal Code Verification

USPS offers Address Verification APIs. You can either make use of their full address verification API or use a simple ZIP code lookup. USPS even has a web interface through which you can verify ZIP codes with USPS. However, there is one major catch in using USPS's free ZIP code verification.

Even though USPS offers a free solution, it may not be the best choice for you if your business requires sending bulk postal mails. It is true even for their address validation API. Hence, most companies often go for a more advanced third-party solution.


PostGrid is a third-party direct mail solution that businesses prefer when it comes to ZIP code validation. The popularity of PostGrid for business applications is understandable considering its features and capabilities.

PostGrid lets you bulk verify entire addresses and not just the ZIP code. All you need is a CSV file of your address data. You can use their API or the web interface for the verification. You also get to automate the entire direct mail process, including personalization, printing, and mailing.

With automation, you don't have to worry about any manual errors or typos. As a result, you can minimize the return rate and ensure optimized execution of your direct mail process.


ZIP code validation is now a necessity for any business that sends regular direct mail to its customers. It saves you valuable time and money you spend on your direct mail campaigns. In addition to this, you can also avoid wastage of resources as ZIP code verification significantly boosts the deliverability rate.

Although USPS offers a free tool to verify zip codes, it is not practical for business applications. The main reason for not using USPS's free tolls is that it does not support bulk verification. On the other hand, third-party solutions like PostGrid are ideal for businesses.

PostGrid provides superior ZIP code verification capabilities. Furthermore, it provides a single fully automated solution for direct mail. As a result, you can significantly minimize the time you spend on the direct mail process and get the best result.

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