Overview
Lob.com provides a US Address Verification API that validates, standardizes, and geocodes US mailing addresses using USPS data, ensuring mail deliverability and cleaning up address databases. It also supports international address verification, address autocomplete, and physical mail sending (postcards, letters, checks) via API. The free test mode allows unlimited verifications against a sandbox environment.
Beginner Tip
Create an account at lob.com and use the test API key (prefixed with `test_`) for free sandbox verification. The verification endpoint is `https://api.lob.com/v1/us_verifications`. Authentication uses HTTP Basic Auth — set the API key as the username with an empty password. Test keys return standardized results but do not charge credits.
Available Data
The kind of data this API exposes, based on its documentation. We could not call the endpoint to confirm the exact field names.
Example Response
Illustrative shape only — we were not able to call this endpoint (it requires credentials or exposes no public sample URL), so the fields below show the kind of data this API returns rather than a recorded response.
{
"status": "success",
"data": {
"result": "Data from Lob.com",
"description": "US Address Verification",
"timestamp": "2025-01-15T10:00:00Z"
}
} Field Reference
deliverability USPS deliverability status: `deliverable`, `deliverable_unnecessary_unit`, `deliverable_incorrect_unit`, `deliverable_missing_unit`, or `undeliverable`. primary_line The standardized first line of the address (street number and name). last_line The standardized city, state, and ZIP+4 code on the last line. components Parsed address components including street number, street name, city, state, zip code, and zip+4. urbanization Urbanization code used for Puerto Rico addresses; empty for continental US addresses. Implementation Example
Calls a real endpoint of this API. Replace any placeholder credentials with your own key.
const url = "https://lob.com/";
// 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
Generated guidance based on this API's documentation, not observed by us. Treat it as a starting point and check against the provider's own error reference.
Metadata Score Breakdown
Estimated from metadata — endpoint not independently tested
Metadata estimate · endpoint not independently tested
Technical Specifications
Related Tags
Similar APIs
View All →US Autocomplete
Smarty's US Autocomplete Pro API provides real-time US address suggestions as users type, returning up to 10 valid USPS-deliverable address candidates per query to reduce data entry errors and speed up checkout flows.
US Extract
Smarty's US Extract API scans any block of unstructured text — emails, documents, web pages — and extracts all US postal addresses it finds, then validates each one against USPS data for deliverability.
US Street Address
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.
VATlayer
VATlayer is a REST API for validating EU VAT numbers in real time against official EU VIES (VAT Information Exchange System) data, returning company name, address, and registration status.
Postman Echo
⭐ Beginner's PickPostman Echo is a free HTTP test server that mirrors back exactly what you send — headers, query parameters, body, cookies, and request method — making it invaluable for debugging API clients and understanding HTTP behavior without needing a real backend.