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Introduction to Lob's Address Verification API
May 31, 2017

Introduction to Lob's Address Verification API

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Joe Singh

Here’s a quick introduction to Lob’s new Address Verifiction API.


Lob’s Address Verification API checks the validity and deliverability of a physical mailing address in the US or internationally. In compliance with USPS standards, it also standardizes and corrects addresses as necessary. Companies leverage Lob’s Address Verification API to maximize the cleanliness of their address data is as clean as possible prior to mailing or storing customer data into CRMs and databases. This enables companies to avoid spending extra time and wasted dollars on undeliverable addresses.

Our Address Verification API is one of the first modern REST APIs to be CASS certified by USPS, which is an indication of software quality that maintains highest accuracy for deliverability, and means that companies who use it upstream can save money by eliminating bad addresses from their mailing list. It will provide clients with industry-leading insight into more than over 156 million domestic addresses and covers 240+ international countries. Each address verification request runs through a rigorous process to ensure deliverability. Addresses are parsed and standardized, and the cleaned-up addresses are validated against USPS.

Address Standardization/Validation

USPS defines a standardized address as one that is fully spelled out, has a correct city and state, is abbreviated with Postal Service standard abbreviations, and is correctly formatted. You ultimately have to arrive at what the USPS calls a complete address: fully spelled out and an exact match with the current Postal Service ZIP+4 index. Using Lob’s API will ensure that your company has complete and machine readable addresses as accepted by USPS.

Once an API request is received by Lob, our Address Verification API will break down the provided address into its individual components and return a detailed deliverability analysis. There are five possible outcomes when a user inputs addresses into Lob’s API:

  1. Deliverable: perfect, or we perfected it by matching it to a single address. Go ahead and send.
  2. Deliverable extra secondary: the building provided exists, but secondary number information (apartment, suite, unit) is invalid. If we remove the secondary information we match to a valid delivery point.
  3. Missing secondary: the address is deliverable, in theory, but is missing secondary information like a unit designation or apartment number. There’s a chance the mail won’t reach its intended recipient until address completion. This would be like mail reaching the correct apartment building but not reaching the correct apartment.
  4. Undeliverable: the address as a whole is not deliverable according to the USPS. However, parts of the address, like the street name or ZIP code, are valid. This package won't reach the destination as formatted, but a few changes will make it correct and mailable.
  5. No-match: this doesn’t exist. We couldn’t find a matching street within the city or ZIP code.

Delivery Point Validation

Lob’s Address Verification API also provides Delivery Point Validation analysis and breaks address strings down into individual components. Every unique deliverable address served by USPS has a 12-digit identifier, which includes a 2-digit delivery point and check digit assigned to it by the USPS.

These digits are internal to USPS, and help ensure the accuracy and deliverability of a particular address (particularly instances when checking for a valid apartment number on a standardized address). Lob’s API verifies the street address and the additional details around a valid secondary designator (apartment, suite, etc.). DPV evaluates the deliverability of a package as a binary outcome instead of validating bits and pieces.

Why Use Address Verification?

By using Lob’s Address Verification API, companies can save time and money on undeliverable mail or packages. CASS certified software, like Lob’s API, has cleared a very high accuracy threshold. It adds missing information and performs delivery point validation. It even uses Locatable Address Conversion System (LACSLink) to update renamed or renumbered addresses.

Lob’s API enables companies to correct addresses in real-time, rather than relying on mail reports back from print vendors or returned mail.

Remaining on the bleeding edge of postal accuracy has never been easier!

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