How do I integrate my Store with USPS for Real-Time Shipping Calculation?

Your 3dcart store can be integrated with the main shipping carriers in order to provide your customers with real-time shipping calculations for their orders.

This guide will show you how to set up your account registrations with USPS and then integrate your credentials to your 3dcart store.

When registering with USPS, you will initially be placed on a Test API server on their system. In order to use USPS on your 3dcart store you will need to have USPS move you to a Production API server. More information on this can be found below.

Register with USPS

To register your USPS account, please follow these steps:

  1. Go to the USPS Web Tools Registration form located here.
  2. Fill out the form as required

After submitting the form, USPS will create your API login account. You will then receive an email with your API account credentials.

These API credentials will need to be entered in your 3dcart Store. However, you will first need to be moved onto USPS' Production API environment.

Additional Information:
Moving to Production API Server

When creating your account, USPS will automatically place you on a testing API server. However, before your credentials can work with your 3dcart store, you will need to have your account moved to USPS' production API server. Therefore, you will need to email the USPS team to let them know they should move you to the Production API server.

Do NOT reply to the email address in which you were sent your API login credentials. Instead, you will need to contact USPS' internet Customer Care team at either of the following:

If you elect to email them, the following message in the email should suffice:


I am using a third-party shopping cart provider, 3dcart. I would like to have my USPS account moved to the production server. I will also need access to the DeliveryConfirmation API as well.

My USPS Account Credentials are the following:


Thank you.

USPS will notify you once the account is moved as requested.

Adding your credentials to your 3dcart Store

Once you have registered and have been moved to the Production API servers for USPS Web Tools, proceed with the following steps to integrate them into your 3dcart Store.

  • Log into your 3dcart Online Store Manager
  • Using the left hand navigation menu, go to Settings ->Shipping
  • Click on the "Enter Settings" button located under Shipping Settings
  • Next to the USPS section, click on "Enter Credentials"
  • Enter your USPS API credentials in the provided fields
  • Click "Save Settings" at the bottom of the page.

You are done integrating your Store to USPS and can now use Real-Time Shipping Calculation for USPS shipping methods.

Please review our additional article on setting up the Shipping Methods

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