Automatic shipping calculations by weight using USPS

To use the USPS shipping rates API, you must first register yourself with USPS to get a USPS username.

  1. Go to
  2. The site owner, must complete the form.
  3. Next you will receive an e-mail from USPS with your username.

Once you have obtained the username, you can now setup USPS in your LinkU Shopping cart.

  1. Login to your website control panel.
  2. Click Online Store.
  3. Click Shipping.
  4. Click Shipping Settings.
  5. Go to the USPS section and select to enable it.
  6. Enter the USPS User ID that was assigned to you.
  7. Select the services you would like to office pricing when a user checks out.
  8. If you provide any free shipping options with a specific USPS service, select that here, along with what countries it is available for.
  9. Click to Save Settings.

After it has been added to the cart, you must reply to the e-mail from USPS and let them know that you need your user ID to be activated for Production. Send them the following:

Hello, we are using a vendors shopping cart, LinkU Shopping Cart from LinkUSystems, Inc., which has already been tested and is currently in use with USPS. Please activate our user ID and API for production.

Hopefully USPS will respond by activating your API Login ID and letting you know of its approval.

That's it! USPS is now setup on your cart. We recommend you do a test checkout on your cart to make sure it works properly. If you encounter any issues during the approval process, please contact support.

Note: In order for this feature to work, you must have a weight assigned to all your products, under the product details.


Feedback and Knowledge Base