Introduction

The Additional Fees SPI is a service provider interface that allows site owners and collaborators to add additional fee calculations that don't come natively with Wix to their site. The SPI allows you to change how apps, such as Wix Stores and Wix Bookings, calculate charges during checkout. Additional fees are calculated and seen in all eCommerce platform pages including cart, checkout, orders, and payments. Examples of additional fees are surcharges based on customer location, special handling during shipping, or gift wrapping.

Wix eCommerce calls the SPI endpoint calculateAdditionalFees() to retrieve the relevant data for a site collaborator to add additional fees. Collaborators can then implement their own logic to calculate additional fees, and return the calculated fee data in the structure provided by Wix eCommerce.

Note that currency in the calculateAdditionalFees response must match your site's currency. You can find the currency of your site using the getPaymentCurrency() function.

Learn more:

• Velo: Custom App Extensions Using SPIs
• Additional Fees SPI custom extension