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Address Matching System API (AMS API)

AMS API is software used to develop address matching software. This software provides access to USPS® matching logic, which allows users to verify the accuracy of ZIP + 4® returns.

Who is AMS API for?

AMS API may be integrated within a manufacturer's product and redistributed by the manufacturer. The DPV®, LACSLink®, RDI™ and eLOT® files can be used in conjunction with the AMS API Developer's Kit.

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What is AMS API?

AMS API is software used to develop address matching software that provides access to USPS matching logic, which allows users to verify the accuracy of ZIP + 4 returns.

AMS API contains the following information:

  • API library(s) for each specific computer platform
  • Interface definition file (ZIP4.H)
  • Test utility (SAMPLE.EXE)
  • Test utility source code
  • Sample configuration data files
  • User documentation

The test utility can be used to ensure the Address Matching System and data files have been installed correctly and to provide access to USPS matching logic, which displays the standardized address returned by the matching engine. Additionally, the AMS software, including but not limited to .DLL files, shared objects, and static objects all expire and cease functionality based on the CASS™ guidelines.

The AMS API Product is updated monthly via Electronic Product Fulfillment.

Note: CASS certification is not a requirement for the AMS API Product. However, to receive automation discounts, users must obtain CASS certification.

Annual License Fee: Pricing varies depending on the products and platforms used.

Licensing information for AMS API can be found here.

What's next?

The AMS API License Agreement requires signature compliance and subscriptions are maintained on a calendar year basis. The RDI Product requires a direct license from the USPS.

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Related Products


The CASS™ certification process is designed in cooperation with the mailing industry to improve the accuracy of postal codes, i.e., Five-Digit ZIP Code®, ZIP + 4®, delivery point (DPCs), and carrier route codes that appear on mailpieces. 


The DPV® Product identifies whether a ZIP + 4® coded address is currently represented in the USPS® delivery file as a known address record. It also allows users to confirm known USPS addresses, as well as, identify potential addressing issues that may hinder delivery.

Enhanced Line of Travel (eLOT®)

The eLOT product allows mailers the ability to sort their mailings in approximate carrier-casing sequence.


The LACSLink® product offers an automated method of obtaining new addresses after a 911 emergency system has been implemented.



To obtain order forms or more information about AMS API, contact the National Customer Support Center at 877-640-0724Call: 877-640-0724