Smarty Streets Integration

Last Updated: June 22, 2026

This guide covers connecting a Smarty (formerly SmartyStreets) account to UltraCart so the platform can verify, standardize, and autocomplete shipping addresses during checkout.

Overview

Smarty is a third-party address verification service. When connected, UltraCart sends the shipping address a customer enters at checkout to Smarty, which checks it against authoritative postal data (USPS CASS data in the U.S., plus international datasets) and returns either a verified/standardized version of the address or an indication that it could not be matched.

UltraCart uses that result in two ways:

Address verification confirms a shipping address is real and deliverable, and can offer the customer a corrected (standardized) version to accept.
Address autocomplete suggests complete addresses as the customer types, reducing typos and abandoned fields.

The verification work happens server-side: UltraCart calls Smarty with your account credentials, so no embedded API key is exposed in the storefront. This integration is what powers the storefront Address Validation feature at checkout. Without an active, enabled Smarty connection, address validation does not run.

Smarty bills for the lookups it performs. Review Usage Limits and Cost Control before enabling on a high-traffic storefront.

Prerequisites

A Smarty account. Sign up at smarty.com/signup.
A Smarty subscription that includes the lookups you intend to use (US Address Verification, International, and/or US Autocomplete).
A Secret Key credential pair from Smarty: an Auth ID and an Auth Token. These are created in the Smarty dashboard under API Keys.
UltraCart account access with permission to edit Configuration → Checkout → Shipping.

Important: Use a Secret Key (Auth ID + Auth Token) pair, not a website/embedded key. Because UltraCart performs verification server-to-server, the secret-key credentials never reach the shopper's browser.

Where to Configure

All Smarty settings live on the Shipping Checkout Options screen:

Configuration → Checkout → Shipping → Checkout Options

Scroll to the Smarty Streets Address Verification panel near the bottom of the page.

Setup

1. Create a Secret Key in Smarty

Sign in at smarty.com.
Open the API Keys area of your account.
Create (or copy) a Secret Key. Note the Auth ID and Auth Token values.
Make sure the key's allowed subscriptions cover US Address Verification, and International and/or US Autocomplete if you plan to use them.

2. Enter your credentials in UltraCart

Go to Configuration → Checkout → Shipping → Checkout Options.
Find the Smarty Streets Address Verification panel.
Check Enable Smarty Streets address verification.
Enter your Auth ID and Auth Token.
Click Save.

For security, UltraCart masks the stored Auth ID and Auth Token (for example ••••••••4446). The fields show only the last few characters. To change a value, type a new full value over the masked one and save; leaving the masked value untouched keeps the existing credential.

3. Choose your verification behavior

With credentials in place, set the behavior toggles described in the Settings Reference:

Verify the shipping address at checkout turns verification on.
Offer the corrected address as a suggestion lets customers accept Smarty's standardized version.
When the customer will not provide a verified address decides what happens when an address can't be confirmed.
Enable address autocomplete turns on type-ahead address suggestions.

Click Save after adjusting these.

4. Confirm the storefront is wired up

Verification and the suggestion/confirm prompts are rendered by the storefront checkout. Confirm your checkout has the Address Validation elements in place, as described in the Address Validation guide.

Settings Reference

Setting	Default	Description

Setting	Default	Description
Enable Smarty Streets address verification	Off	Master switch for the integration. Must be on for any verification or autocomplete to occur.
Auth ID	(empty)	The Auth ID half of your Smarty secret key. Masked once saved.
Auth Token	(empty)	The Auth Token half of your Smarty secret key. Masked once saved.
Verify the shipping address at checkout	Off	When on, the shipping address entered at checkout is sent to Smarty for verification.
Offer the corrected address as a suggestion	Off	When on, if Smarty returns a standardized version that differs from what the customer typed, the customer is shown a "Did you mean…?" prompt to accept the corrected address.
When the customer will not provide a verified address	Require a phone number	Controls what happens when an address cannot be verified and the customer declines the suggested correction. Options: Allow the order through, Require a phone number, Block the order. See How Verification Behaves at Checkout.
Enable address autocomplete	Off	Turns on type-ahead address suggestions as the customer types. Handled server-side, so no embedded key is required in the storefront.
Monthly autocomplete request limit	100	Caps autocomplete lookups per month. `0` = unlimited.
Monthly verification request limit	1000	Caps verification lookups per month. `0` = unlimited.

How Verification Behaves at Checkout

When Verify the shipping address at checkout is enabled, the address a customer enters is checked against Smarty before the order can proceed. There are three possible outcomes:

Exact match — the address is deliverable and matches what the customer typed. Checkout continues.
Standardized correction — Smarty returns a cleaned-up version (for example, fixing the ZIP+4 or street suffix). If Offer the corrected address as a suggestion is on, the customer sees a "Did you mean the suggested address?" prompt and can accept the correction or keep their entry.
Cannot verify — Smarty can't confirm the address. The When the customer will not provide a verified address setting decides the fallback, with three choices:
- Allow the order through — the customer may proceed with their unverified address; no extra prompt is shown.
- Require a phone number — the customer may proceed but must supply a phone number, so you can reach them about delivery.
- Block the order — the order cannot be completed until the customer enters an address Smarty can verify.

The actual prompts the customer sees (the suggestion modal and the confirm/block modal) are part of the storefront checkout. See the Address Validation guide for how those modals are configured and what the shopper experiences.

Usage Limits and Cost Control

Smarty charges per lookup, so UltraCart provides two monthly caps to protect against unexpected cost:

Monthly verification request limit — the maximum number of address verification lookups UltraCart will perform per calendar month. Defaults to 1000.
Monthly autocomplete request limit — the maximum number of autocomplete lookups per calendar month. Defaults to 100.

Set either value to 0 for unlimited. When a limit is reached, UltraCart stops sending that type of request to Smarty for the remainder of the month, and checkout proceeds without that assistance until the next month resets the counter.

Set these limits in line with your Smarty plan's included volume so a traffic spike doesn't run up overage charges. For a busy storefront, raise the verification limit (or set it to 0) only after confirming your Smarty subscription can absorb the volume.

Troubleshooting

Address validation never appears at checkout

Symptoms: Customers are never prompted to confirm or correct an address.

Cause: The integration is disabled, credentials are missing/invalid, or the storefront checkout is missing the Address Validation elements.

Solution:

Confirm Enable Smarty Streets address verification and Verify the shipping address at checkout are both checked.
Re-enter the Auth ID and Auth Token (type fresh full values over the masked ones) and save.
Verify the checkout has the suggestion and confirm elements in place — see the Address Validation guide.

Verification stops partway through the month

Symptoms: Address validation worked earlier in the month, then stopped.

Cause: The Monthly verification request limit was reached.

Solution: Raise the limit or set it to 0 for unlimited, confirming your Smarty plan can absorb the volume. The counter resets at the start of each calendar month.

Credentials appear masked and won't update

Symptoms: The Auth ID/Auth Token fields show masked dots and edits don't seem to take.

Cause: UltraCart masks stored credentials and only replaces them when a new full value is typed in.

Solution: Clear the field, type the complete new Auth ID / Auth Token value, and click Save.

Autocomplete isn't suggesting addresses

Symptoms: No type-ahead suggestions while entering an address.