USPS address validation API and list service
Verify and standardize postal addresses
Address verification is our passion. It's what we do. We'll take care of your addresses to help you take care of your customers.
Verify addresses on website forms
Now it's faster and easier than ever to verify addresses on your website. Help your customers provide valid address data by verifying it in real-time with our API. Display multiple matches if the address is ambiguous, and alert them when the address is invalid. Your shipments will be cheaper and arrive faster, and your customers will be satisfied knowing that their addresses were submitted correctly the first time.
What is address verification?
Address verification, or address validation, is used to determine the deliverability of a specific address. During the address verification process, addresses are cleaned and standardized according to USPS guidelines. Spelling mistakes are corrected, and the standard 5-digit ZIP Code is expanded to the more precise ZIP+4 Code. This process can be used to qualify for discounts on bulk mailings and to ensure timely delivery of e-commerce shipments.
Blazing fast speeds
Buckle up, because we're fast. The engine that powers our address verification service is so fast that you can have the results back to you immediately. Lists containing tens of thousands of addresses will be finished in a minute or two, and lookups to our API will receive a response in less than 100ms. Try it for yourself! In most cases, your addresses will be ready before you are.
Enjoy no minimum purchases or binding contracts. Our prices are the most affordable in the industry, from just a few addresses to millions — and beyond, with our Unlimited plans. Sign up for free and get 250 free API lookups every month, and preview any of your lists for no charge. We also grant free address verification to qualifying nonprofits and business startups.
Get mailing discounts
Address verification must be performed for every letter or parcel handled by the US Postal Service. To save them time and money, the USPS licenses vendors like SmartyStreets to verify addresses before you send out your mailing. Just run your address list through LiveAddress for Lists, our CASS-Certified™ list service. You'll get the CASS™ Summary Report (PS 3553) that you need to take to the post office with your mailing to receive automation rate discounts.