Add a Service Plugin Extension in Studio Two

A service plugin is custom backend logic that Wix calls during one of its own flows, such as checkout or booking.

Follow the instructions below to:

  1. Add a service plugin extension to your site project.
  2. Customize the plugin.
  3. Check the plugin.
  4. Publish your site with the plugin.

Note: You can also ask Aria, Wix's AI assistant, to create and customize the extension.

Step 1 | Add a service plugin

To add a service plugin:

  1. In the Studio Two editor, open the Code tab.

  2. In the VS Code sidebar, open the Wix Extension Builder.

    the Wix Extension Builder in the VS Code activity bar

  3. Under Create an Extension, choose Backend, then Service Plugin.

  4. Fill in the form:

    • Which service plugin do you want to create: The Wix service this plugin extends. The list is fixed. For example, choose Ecom Additional Fees. For every type the Builder offers, see Available Service Plugins.
    • Name: The folder and file name. The name can be at most 19 characters. Choosing a plugin fills this in with a slug of that plugin, shortened to 19 characters when the slug is longer. For example, Ecom Additional Fees fills ecom-additional-fee.

  5. Click Generate.

You can find the new files under src/extensions/backend/service-plugins/<plugin-name>/. The extension is registered in your project's extensions.ts and listed under My Extensions. For what each file is for, see Service Plugin Extension Files and Code.

Step 2 | Customize your service plugin

You can edit the generated files to match the service behavior you need. Change the code yourself, or ask the AI in the Code tab to help. When you're happy with the plugin, move on to the next step.

For the handler, the configuration file, and the response your plugin type must return, see Build a Service Plugin in Studio Two.

For example, for an Ecom Additional Fees plugin:

  1. Open <plugin-name>.ts.
  2. Return the fees you want instead of an empty additionalFees array.
  3. Save the file.

When the checkout flow requests additional fees, your plugin returns those values.

Step 3 | Check the plugin

To check a service plugin, trigger the Wix flow that uses it. The trigger differs per plugin type. For example, for an Ecom Additional Fees plugin:

  1. Install a Wix app that uses Wix eCommerce, such as Wix Stores, and add at least 1 product.
  2. Go through checkout on your live or preview site to trigger the plugin.
  3. To confirm the handler ran, even if the change doesn't visibly appear in the checkout UI, write a temporary log entry in your handler with the monitoring client, then check the Logs page in the site dashboard under Developer Tools. console output doesn't appear there. See Write Log Messages in Studio Two.

Note: Calling the underlying eCommerce APIs directly doesn't reach the plugin. The handler only runs as part of an actual checkout flow on the site itself.

Step 4 | Publish your site

When you're ready, click Publish in the Studio Two editor to ship the extension with your site.

See also

Last updated: 2 November 2026

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