WP Plugin Setup

System Requirements

Website Requirements for Slibstream

Slibstream requires 1. and 2. (3. is optional):

  1. Self hosted WordPress website
  2. WooCommerce plugin installed
  3. (Optional) WordPress Multi Language [WPML]

What is a “Self hosted WordPress website”?

In a nutshell, self hosting your WordPress site means downloading your own copy of the WordPress content management system (CMS), finding a domain provider, and signing up for a hosting service to host your site on the Internet

Slibstream is designed to run on self hosted WordPress websites running the WooCommerce plugin. WPML is optional. Our demo self hosted WordPress shop runs WooCommerce with WPML.

API Key Requirements for Slibstream

Slibstream is a paid (premium) service. Find your API key here or create an account to use Slibstream.

Slibstream requires a valid API key to function.

PHP Version Requirements for Slibstream

Slibstream has been tested on PHP 7.3 + PHP 7.4.

It is unlikely that Slibstream will run on PHP 5.X because it is no longer supported.

PHP 7.0, PHP 7.1, PHP 7.2 have security fixes.

It is therefore recommended that you run Slibstream on PHP 7.3 or PHP 7.4.

WordPress and WooCommerce Version Requirements

We aim to keep Slibstream running and functioning correctly on the latest versions of WordPress, WooCommerce and WPML.

It is unlikely Slibstream will work if you are running outdated versions these plugins.

WP Plugin Setup

Custom WordPress Theme Integration Requirements

Good news WordPress developers! We have coded Slibstream inline with the latest WooCommerce API standards and tested it thoroughly works with WPML multi currency.

Browse our demo site to see Slibstream in action.

There Are 3 Key WooCommerce Components That Slibstream Hooks Into

Slibstream relies on the following WordPress hooks to display the Customs Duty on the basket and checkout pages.

WooCommerce hooks that display the Customs Duty Total

add_action('woocommerce_after_cart', array($this, 'debug_output'));
add_action('woocommerce_after_checkout_form', array($this, 'debug_output'));

WooCommerce hook that gets the customs duty data from the Slibstream API

add_action('woocommerce_cart_calculate_fees', array($this, 'slibstream_tax_api_request'));

WooCommerce filter that integrates Slibstream with WPML (if WPML is installed)

add_filter('wcml_client_currency', array($this,'wpml_woocommerce_currency'));

Please do not disable these filters and hooks if you are developing a custom WordPress theme and intend to use Slibstream.

Happy coding!

WP Plugin Setup

A Visual Guide To The Slibstream Plugin Settings Page In The WordPress Dashboard


To view your Slibstream plugin settings page navigate to:

WordPress Dashboard >> Slibstream

Settings Overview

  1. API Key
    This is your unique Slibstream API key. This connects your WooCommerce shop to our API. Manage your API key, billing and more in your account by logging in.
  2. Itemise Duty Costs
    Display 1 line total or display the cost components (multiple line costs) that make up the customs duty cost
  3. Hide Duty Costs if 0.00
    Turn on to hide customs duty on the basket and checkout page if it is 0.00 (none to pay).
  4. Carrier
    Select your preferred carrier – different carriers may charge different fees
  5. Shipping Method
    Select your preferred shipping method – different carriers/shipping methods may charge different fees
  6. Disable Calculations on Basket Page
    Turn on to disable Slibstream on the basket page to reduce the amount of API requests
  7. Debug Mode
    Turn on to display success and error output on the basket and checkout page. This is only visible to WooCommerce managers and WordPress Administrators (whilst logged in).
WP Plugin Setup

How to Setup the Slibstream WordPress Plugin for WooCommerce

Slibstream Customs Duty WordPress Plugin For WooCommerce Setup.

Please read our system requirements guide.

Step 1

Install the Slibstream WordPress plugin by logging into your WordPress dashboard. Navigate to:

WordPress Dashboard >> Plugins >> Add New

Step 2

Search for: Slibstream

Click Install

Step 3

Click Activate

Step 4

Slibstream is a premium (paid) service. To use Slibstream you must have a Slibstream account.

Create a Slibstream account or Login to your existing Slibstream account

Step 5

To find your existing Slibstream API Key navigate to:

Current API Keys from within your account area.


(1) Your API Key is automatically generated (copy this). Your API Key will be a unique string of characters and numbers.

(2) Enter the domain name or sub domain of your website.

Your domain must be entered in the following format without https://, without www. and without a page name or trailing slash.

Domain Example:
Subdomain Example:

(3) Press Update


Slibstream will only work if you have entered your domain name or subdomain name correctly. A valid API is required to use Slibstream and 1 API Key can only be used on 1 website.

Step 6

Enter your API Key into the Slibstream plugin settings page in your WordPress website. Then press update. To do this navigate to:

WordPress Dashboard >> Slibstream


(1) Paste your Slibstream API Key

(2) Click to find your API Key in your Slibstream account

Step 7

A green “API Key Valid” message will display if you have completed the steps above correctly.

This success message signifies that your Slibstream plugin is successfully connected to our API using your API Key.

Please complete the steps above again if you do not see this green message.


Step 8

Ensure your WooCommerce shop address is fully completed.

Slibstream will only work if it knows your Ship from address. To do this navigate to:

WordPress Dashboard >> WooCommece >> Settings


Once you have entered your physical shop address you will see green ticks next to your address in your Slibstream plugin settings. Any red crosses will need to be fixed. Navigate to:

WordPress Dashboard >> Slibstream


Step 9

To enable customs duty calculations for WooCommerce products you must configure each product individually.

Go to each product and enter the HS code for the product and ensure each of the following product options has a correct value. Your HS code will be different for different types of products.

Slibstream requires 6 fields per product

  1. Price or Sale Price
  2. SKU
  3. Product Name
  4. Short Description
  5. Weight
  6. HS Code

Slibstream does not search or create HS Codes for products. We have created this HS Code guide with links to free tools to help you find your product HS Code.


(1) Product HS Code of the product sold

(2) All 6 required fields should all say “Yes”. Correct any that do not display “Yes”.

What Is A HS Code? How Do I Find This?

Step 10

We suggest you turn on “Debug Mode” in your Slibstream plugin.

This mode will display output on the checkout page which is only visible to:

  • WooCommerce managers (whilst they are logged into WordPress)
  • WordPress webste administrators (whilst they are logged into WordPress).

Debug mode will help you to determine if Slibstream is working correctly. Navigate to:

WordPress Dashboard >> Slibstream

Turn Debug Mode to “On”


Step 11

Go to your WooCommerce shop, add a product to cart and continue to the checkout page. Once you have entered your billing or shipping address you will see the customs duty due.


(1) Enter your billing address

(2) Customs Duty Total displays

Slibstream should now be running correctly!

If you experience any errors, ensure debug mode (Step 10.) is on and refer to our error code document. Often the debug output will describe the issue to fix if there is a problem. Product related problems are usually easy to fix.

Here’s how to troubleshoot 2 common problems:

Finally, customs duty is only calculated for country A to country B deliveries. There are other circumstances when Customs Duty might be zero. It’s important to understand that there are instances when no customs duty is payable and Slibstream may be functioning correctly.