US Street Address API

Data Validation / API Key Intermediate HTTPS CORS
Varies by plan (check documentation)

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

Example Response

JSON Response
{
  "input": "test@example.com",
  "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

Request
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.

Metadata Score Breakdown

Estimated from metadata — endpoint not independently tested

This score is estimated from observable metadata — HTTPS support, authentication model, declared CORS, and documentation reachability — because the API requires authentication or exposes no publicly testable endpoint. The five-signal breakdown is only shown for live-tested APIs.

Metadata estimate · endpoint not independently tested

Technical Specifications

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

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