A site plugin is a custom element that renders in a slot on a widget built by a Wix business solution, such as the Wix eCommerce Side Cart, so you can extend that widget with your own content. A slot is a UI placeholder in the widget where a site plugin can render.
For when to use a site plugin, how slots work, and the plugin's runtime contexts and permissions, see Site Plugins.
A site plugin in a Studio Two project is a configuration file, the custom element that renders in the slot, and a settings panel:
HTMLElement.In a Studio Two site, you place a plugin in its slot from the editor, so the slot must be on a page that you can open in the editor, such as the Side Cart. The Side Cart is a preview of the Cart page that opens on the side of the site's pages.
The Wix eCommerce Checkout page has slots, but it isn't one of the pages you can open in the editor.
The Wix Stores product and category pages and the Wix Events pages don't have slots, although the Wix Extension Builder lists slots for them.
Last updated: 2 November 2026