Creators of WooCommerce and JigoShop plugins.

We specialise in shipping and payments.

To purchase our products please head over to ExtensionWorks


Shawn Smith -



  1. Upload the plugin folder to the ‘/wp-content/plugins/’ directory.
  2. Activate the plugin through the ‘Plugins’ menu in WordPress.
  3. You will be prompted to install the Extensionworks Framework click on the link and install it.
  4. Activate the Extensionworks Framework
  5. Thats it – you can now configure the plugin.


To activate the ExtensionWorks Licence go to: Dashboard > ExtensionWorks Licences

Product Information


Setting up WooCommerce

The USPS Shipping Extension only works if you set the country of origin to the United States and the default currency to the U.S. dollar. To do that, go to WooCommerce --> Settings --> General. You should see the following screen.


Make sure you save your changes before moving forward. Next, go to WooCommerce --> Settings and then click on the shipping tab to bring up the shipping options. Check the following screenshot for a quick reference.


If your screen doesn’t look like this, something probably went wrong somewhere along the line. Click on the Woo Commerce button on the left bar. Notice how “settings” is highlighted

General Shipping Options.

The first thing we need to check are the general shipping options. If shipping isn’t enabled, the USPS Shipping Extension definitely won’t work. You also have to enable the shipping calculator, or the USPS Shipping Extension won’t be able to calculate your customers’ shipping rates.


You are now finished setting up the general shipping options. The next part is absolutely essential, so keep following along.

USPS Shipping Extension Options.

Stay on the same screen, and click on the USPS link under shipping options. It’s this one:


You will be taken to the USPS Shipping Extension screen. You should see the following options:

To view a larger image please view the PDF Can also be found at the bottom of the page. The PDF provides the areas that need to be enabled.



USPS requires you to be using US dollars and United States as your base country. Works best using inches and pounds.


General Setting
Enable/ Disable: Tick to enable to function.
Method Title: This displays the name of the shipping carrier.
Origin Postcode: This is where your shipping will start from.
Method Availability: You can select specific Countries, or all Countries.
Debug mode: Used for testing the product.


Packing Setting
Handling Fee or Discount fee: You can add or subtract an amount from your shipping rate. Enter amount +2.50 or -2.50, you can also add +2% or -2%

You can also tick the option to apply the handling fee to the value of the cart.

Un-packable Products Setting 
Send un-packable products directly: Products that do not fit into any custom boxes, the product dimensions will be sent to the Shipping Carrier (API) to determine a rate.
Remove un-packable products: The products that do not fit into any custom boxes will not have a shipping rate returned from the shipping carrier.
Terminate calculate Process: There are no custom boxes (set up in the admin area) to calculate a shipping rate, the API request will be terminated. No rate will be returned from the Shipping Carrier.


Parcel Packing Method / Choose Packing method

Packing Method


Custom Boxes
To use a certain custom box for your shipping you will need to Tick the option: Select Box for the custom box you would like to use. 

If your shipping Companies offers Predefined boxes they will already be pre-populated in the custom box area. You will need to Select the predefined boxes you would like to use.

Adding a custom box please enter the following: 

  • Outer Length, Outer Width, Outer Height 
  • Inner Length, Inner Width, Inner Height
  • Box Weight 
  • Maximum Weight  
  • Label
  • Weight ( tick if only shipping with weight only)
  • Letter ( tick if you would like to use as a letter option) 

Save you settings. Very Important.

Then go and Select the custom boxes you would like to use. Tick the selected options.
Save your Settings

Shipping Method Services
 Enable customize shipping methods / this needs to be ticked to enable the Services.
Parcel / Letter Shipping Method Services: Tick to enable you to select the Shipping Services you wish to offer on your Website.


Rate Options
Select shipping rate to display: All, Cheapest Rate, Highest Rate.
Select shipping order to display: None, From low to high or From high to low.
Fallback Name: The Label for the Fallback Price offered.
Fallback: If the shipping method returns no matching rates, offer this amount for the shipping so the customer can still checkout. Leave blank to disable.


Plugin Setting

USPS shipping rate type: Choose Online Rates or Offline rates.

The Online rates are not applicable to all the shipping Services.

For full details please view here:

Adding Multiple Origin Zip Codes/ Post Codes

The default ( global ) origin Zip Code is set up in the USPS admin area.

To use multiple Post codes option go to: Products ( individual product area) /Product Data/ Shipping.

Here you can add the specific information:
WooCommerce USPS requires you to enter to Post code only.


That's it your done.


The box packer is volume based. This will in most cases provide good results, but will never be as accurate as a real person packing a box (see BIN Packing Problem) therefore it is important you understand that packing results are as accurate as they can be and any anomalies should be accepted.



Please check the following:


SimpleXML installed

The plugin needs to be able to talk to USPS API. For this it uses wp_remote_post which makes use of fsockopen/CURL.

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