M
API Matrix

US Street Address API

Data Validation / API Key Intermediate HTTPS CORS
Varies by plan (check documentation)
52 Score
Grade D
Visit Official Site Compare Alternatives

Overview

The Smarty US Street Address API validates and enriches US postal addresses in real time, returning standardized components like delivery line, city, state, ZIP+4, and county FIPS code. It also appends geocoded latitude/longitude and vacancy data to each verified address. This is the industry standard for e-commerce checkout, CRM cleansing, and logistics routing where address accuracy matters.

💡

Beginner Tip

Sign up at smarty.com to get a free API key that covers 250 lookups per month; pass it as the auth-id query parameter. Test your first request by sending a single street address as the street parameter — the response array will be empty if the address is undeliverable.

Available Data

US Street Address data via REST API
JSON-formatted response data
Requires API key authentication

Example Response

JSON Response 
{
  "input": "[email protected]",
  "is_valid": true,
  "format_valid": true,
  "details": "Input passes all validation checks"
}

Field Reference

delivery_line_1 Standardized primary address line, e.g., 1600 Amphitheatre Pkwy.
last_line City, state abbreviation, and ZIP+4 on one line, e.g., Mountain View CA 94043-1351.
components.zipcode Five-digit ZIP code extracted from the verified address.
metadata.latitude Geocoded latitude coordinate for this address.
metadata.longitude Geocoded longitude coordinate for this address.
analysis.dpv_match_code USPS Delivery Point Validation result: Y=confirmed, S=partial, D=default, N=not confirmed.

Implementation Example 

const url = "https://www.smarty.com/docs/cloud/us-street-api";
// Replace headers or query params with the values required by this API.
const response = await fetch(url, {
  headers: {
  "X-API-Key": "YOUR_API_KEY"
  }
});
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

Empty response array (address not found) The input address does not match any USPS deliverable address, or is a PO Box that needs a different endpoint.
✓ Check for typos in the street number and ZIP code; use the US ZIP Code API for PO Box lookups.
401 Unauthorized The auth-id or auth-token query parameters are missing or incorrect.
✓ Append ?auth-id=YOUR_KEY&auth-token=YOUR_TOKEN to the request URL and verify the credentials match your Smarty account.
Multiple records returned for one address An ambiguous address can match several deliverable variations.
✓ Use the first result (index 0) which represents the best match, or display all candidates to the user for selection.

Matrix Score Breakdown

🌐 Reachability 0/30
⚡ Speed 20/20
🔒 Security 15/15
🛠 Developer XP 17/20
✓ Reliability 0/15

Partially tested on Apr 5, 2026

Technical Specifications

Auth API Key
HTTPS REQUIRED
CORS YES
Category Data Validation
Difficulty Intermediate
Verified: 2026-04-04

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