Glossary Item Box

Squirrelcart v6.1.0

USPS Web Tools


USPS Web Tools® is a free service offered by the U.S.Postal Service. You can learn more about it here:

While USPS Web Tools® can be used to print USPS shipping labels, those labels do not include postage. Postage must be purchased at the post office when you drop off the package.

If you are looking for a way to print postage paid USPS shipping labels, we recommend enabling Endicia instead of USPS Web Tools. Endicia is an approved USPS partner. With Endicia, Squirrelcart can generate postage paid labels. You can schedule pickups, get shipping discounts, and much more.

Squirrelcart supports Real Time RatesShipments, and Track/Confirm for USPS, for shipments shipping from the US to all addresses that are serviced by USPS.

APIs Supported

USPS supplies information via APIs. The following APIs are used by Squirrelcart:

USPS Web Tools requires CURL OR fsockopen support, and OpenSSL.
Enabling USPS Web Tools
  1. Register
    Register online to use USPS Web Tools at the following URL: 
  2. Wait for Email
    Once your registration is complete, you will receive a username and password to access USPS Web Tools via email.
  3. Call USPS to get access to production
    The email will tell you to test, and then call a toll free number to get access to their production servers. There is no need to test, as we have done plenty of testing with their APIs. Reply to the email or call their support phone number, and ask to have your account given access to their production servers. You will need access to all of the APIs listed above, so you may want to cut and paste them into the email.
  4. Open the USPS Shipping Courier record in Squirrelcart's control panel
  5. Check the Enabled field
  6. Check the RTR Enabled field
  7. Enter Username
    Enter your username provided by USPS in the RTR Username field.
  8. Enable Services
    Check the boxes next to the shipping methods you want to offer.
Rate Accuracy

In order to make the rates presented to your customers as accurate as possible, we recommend that you enable the "Ship as a Separate Package" field on products that are shipping in separate boxes. You then need to specify dimensions below the field. While this will increase the accuracy of the rates presented, it is still possible for the rates to differ from what your actual costs are. This is due to the fact that USPS does not allow you to pass width, length, or height to them to determine which services are valid. Because of this, Squirrelcart will make it's best attempt to eliminate rates returned that do not meet your product's dimensions.



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