Address Verification, Correction and ZIP+4 Lookup API

NetZipCode for .NET BoxNetZipCode for .NET API allows you to quickly and easily build ZIP+4 lookup, address verification plus address correction into your custom applications. The delivery address is checked for proper Postal Service format and standardized if necessary. Spelling corrections are made and the address is split into USPS standard components. One year USPS database subscription is included.

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  • Address Verification - Real-time or batch address verification and correction
  • Address Correction - Correct spelling errors, standardize addresses and append ZIP+4
  • Address Parsing - Split street addresses into 7 separate elements
  • Unlimited Processing Volume - No processing limits or restrictions with the included USPS database
- Quarterly Updates -- Monthly Updates -
USPS reports that almost
5 of every 100 pieces of mail are
returned undeliverable-as-addressed.
  • $399
  • $599
  • $999
  • $999
  • $1499
  • $2499
  • Single Database License
  • 2-Database License
  • 5-Database License
  • Please contact us for additional pricing information

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NetZipCode for .NET Demonstration

How NetZipCode Works

NetZipCode for .NET follows the US Postal Service “one component failure rule” to find a correct address match. This rule permits an address match if no more than one address component mismatch exists, where a “component” is defined as a pre-directional, street name, street suffix, or a post-directional.

Consider the following address: 100 E MAIN ST N

This address has all four components. If one of the components has to be added, changed, or deleted to achieve a unique match, NetZipCode will correct the address and return the ZIP+4. Under current USPS address matching rules, if more than one component is incorrect, no match is allowed. If adding, changing or deleting a component results in multiple matches, NetZipCode will return a list of all matching addresses. The priority is to add a suffix first, before adding a directional. If there is no match, change or delete the suffix. Finally, change or delete a directional.

An array of flags is returned for each address giving you important information about the status of the matching process such as why the matching failed or what corrections were necessary in order to achieve a match. Also returned is the Address Type allowing you to identify Street, Military, PO Box, Rural Route, Highway Contract or General Delivery addresses and process them accordingly.


  • Save Money on Postage - verify addresses before you ship or mail
  • Catch Data-Input Errors - virtually eliminating undeliverable addresses
  • Save Keying Time - city/state is returned from 5-digit ZIP Code
  • Unlimited Processing Volume - no automatic database expiration
  • Free Database Updates for a full year
  • High-Performance, Local API and Database for Security and Speed - no remote server dependency


  • Addresses are standardized to USPS recommended abbreviations
  • Built-in ZIP Code distance and radius calculations
  • Parse street addresses into 7 separate components
  • Proper-case conversion for more attractive data presentation
  • Designed for use with C#, VB.NET and any other .NET-compatible programming language

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