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ZIP Code Validator

DeveloperText

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INPUT

Auto Process

OUTPUT

Client Side

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Guide

ZIP Code Validator

Quickly validate US ZIP codes to check if they follow the correct format. This tool supports both standard 5-digit ZIP codes (e.g., 90210) and ZIP+4 codes (e.g., 90210-1234). Enter one or more ZIP codes to instantly see which are valid and which are not.

How to Use

Enter one ZIP code per line in the input field
Results appear automatically as you type
Each ZIP code is marked as Valid or Invalid with its format type
Click “Try an example” to see sample ZIP codes and their validation results

Features

Dual Format Support – Validates both 5-digit and ZIP+4 format codes
Bulk Validation – Check multiple ZIP codes at once, one per line
Real-Time Results – Validation runs automatically as you type
Clear Summary – See total count of valid and invalid codes at a glance

 FAQ

What is the difference between a 5-digit ZIP code and a ZIP+4 code?

A 5-digit ZIP code identifies a general delivery area such as a city or town. A ZIP+4 code adds a four-digit suffix separated by a hyphen, which narrows delivery to a specific block, building, or group of addresses within that area.
Why were ZIP codes introduced in the United States?

ZIP codes were introduced in 1963 by the United States Postal Service to improve mail sorting and delivery efficiency. The acronym ZIP stands for Zone Improvement Plan, reflecting the goal of speeding up mail routing across the country.
Are all 5-digit number combinations valid ZIP codes?

No. While the format allows any 5-digit combination from 00000 to 99999, the USPS only assigns specific ranges to actual geographic areas. Many combinations are unassigned or reserved and do not correspond to a real delivery location.