A site plugin is a custom element that fills a predefined slot on a Wix business-solution widget.
Follow the instructions below to:
Note: You can also ask Aria, Wix's AI assistant, to create and customize the extension.
Make sure that your site has a page with the slot the plugin fills, and that you can open the page in the editor. For the slots you can use in a Studio Two site, see About Site Plugins.
The example in this article adds a plugin to the Side Cart, a preview of the Cart page that opens on the side of the site's pages.
To follow the example, install Wix Stores, which adds the Side Cart to your site.
The extension form's What would you like to extend? dropdown lists slots from several Wix business solutions, regardless of whether they're installed on your site. It also lists slots that you can't fill from the Studio Two editor, such as the slots on the Wix Stores product page and the Checkout page. Each option shows the widget name and the slot ID.
For each widget's slots and where each slot appears, see About Slots. Its screenshots might not match Studio Two.
To add a site plugin:
In the Studio Two editor, open the Code tab.
In the VS Code sidebar, open the Wix Extension Builder.

Under Create an Extension, choose Site, then Site Plugin.
Fill in the form:
side-cart:header:after-1.Side Cart Note.Click Generate.
Generate derives the plugin folder from the name, in lowercase with hyphens. For example, Side Cart Note becomes side-cart-note. A single-word name gets a -plugin suffix. For example, Banner becomes banner-plugin.
You can find the new files under src/extensions/site/plugins/<plugin-folder>/, and the plugin's logo in public/. The extension is registered in your project's extensions.ts and listed under My Extensions. For what each file is for, see Site Plugin Extension Files and Code.
You can edit the generated files to match the look and 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 example, to update the plugin text:
<plugin-folder>.tsx.render() method, change the paragraph text to Hello world!.When the plugin appears in its slot, the paragraph shows Hello world!.
Studio Two doesn't place the plugin in its slot when you generate it. You place it in the editor, from the Plugin Market of the widget that has the slot.
The Plugin Market lists the plugins for the widget's slots, both the plugins in your site project and plugins from other apps.
To place the plugin in its slot:
If the page dropdown lists Side Cart more than once, repeat these steps for each one, so the plugin is in the Side Cart that your live site opens.
Site visitors see the plugin after you publish your site.
To publish and check the plugin:
If Add to Cart doesn't open the Side Cart, the button is set to another action, such as going to the Cart page. For the button's settings, see Customizing the Side Cart.
Last updated: 2 November 2026