US Address Validator, Autocomplete & USPS

Free client-side US address validator and autocomplete tool. Parse, standardise to USPS Publication 28 format, check ZIP state alignment, and export JSON.

Live Address Search & Standardization

USPS Pub 28 CASS

Type a street address, city, state, or landmark. Matches will suggest automatically.

Quick Samples:
✓ Valid Standard US Address Format
Official USPS Standardized Mailing Format:
1600 AMPHITHEATRE PKWY MOUNTAIN VIEW, CA 94043-1351
Street Number 1600
Pre-Directional —
Street Name AMPHITHEATRE
Suffix / Type PKWY
Post-Directional —
Secondary Unit —
City MOUNTAIN VIEW
State CA
5-Digit ZIP 94043
ZIP+4 Add-On 1351
State ZIP Alignment Valid (CA Range: 90000–96199)
Delivery Point Check Complete Delivery Address
Parsed CASS JSON Output 
{
  "delivery_line_1": "1600 AMPHITHEATRE PKWY",
  "last_line": "MOUNTAIN VIEW, CA 94043-1351",
  "components": {
    "primary_number": "1600",
    "street_name": "AMPHITHEATRE",
    "street_suffix": "PKWY",
    "city_name": "MOUNTAIN VIEW",
    "state_abbreviation": "CA",
    "zipcode": "94043",
    "plus4_code": "1351"
  },
  "metadata": {
    "carrier_route": "C001",
    "rdi": "Commercial",
    "zip_state_valid": true,
    "cass_standardized": true
  }
}

About this tool

How to use it

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Why it matters

Unstandardized shipping addresses cause delivery delays, carrier return-to-sender surcharges, and lost packages. USPS Publication 28 sets clear rules for postal formatting, uppercase capitalizations, and standardized secondary unit designations. This tool provides developers, eCommerce merchants, and shippers with instant address validation and parsing without requiring paid API subscriptions or transmitting sensitive customer names and street addresses over remote networks.

When to use it

Use when validating customer shipping information during checkout, standardizing legacy CRM customer databases, formatting postal envelope labels, or testing address parsing algorithms.

Common questions

What is USPS Publication 28?

USPS Publication 28 is the official standard issued by the United States Postal Service defining standard address abbreviations, street suffixes, secondary unit designators (APT, STE, FL), and directional indicators to optimize automated mail sorting machinery.

How does the offline ZIP code range validation work?

Every US state and territory is assigned specific 3-digit and 5-digit ZIP code ranges by the Postal Service (e.g., California spans 90000–96199, New York spans 10000–14999). This tool validates whether the entered ZIP code accurately corresponds to the supplied state.

What is CASS standardization?

Coding Accuracy Support System (CASS) is an address verification standard used by the USPS to verify that an address matches official delivery standards, including all-caps formatting, standard suffix abbreviations, and ZIP+4 structure.

Is my address or customer data private?

Yes, 100%. All autocomplete matching, parsing, and regex standardization run purely in your local browser. Zero address details or customer data are ever transmitted to any external server.