The customer is on the product page with the coffee in hand, and the French press belongs right there. With “Add-ons,” you display selected accessories in a box below the purchase button, and the customer adds them in the same transaction. No searching, no detour back to the cart, and no extra marketing needed to close the sale.
One checkbox, and the item is added
The box is called “Add to Cart With” and is located at the bottom of the checkout area on the product page. You decide which items appear in it. The customer checks the box, clicks “Add to Cart,” and both the main item and the add-on are added to the cart at once.
Each add-on becomes its own item on the order with its own price and item number. There’s no confusion at the packing table about what goes in the box, and the accounting looks just as it always does.
The customer can choose the color or size of the add-on
If the accessory is an item with variants, a drop-down menu appears the moment the customer checks the box. The customer selects a color or size without leaving the product page, and that specific variant is included in the order. If there’s only one option, it’s selected automatically, and if the customer forgets to choose, a clear message appears instead of the option being silently omitted.

Set it up for a single product or an entire category
Enter the product IDs of the items to be offered in a field on the main product. Separate multiple items with commas. If you don’t fill in the field on the product, the theme will look further in the product’s main category and then up through the parent categories. If the entire “Coffee” category is to offer the same three items, you simply enter them in one place instead of on every single product.
Items that have been removed from the website are never displayed as add-ons, so you don’t need to clean up the fields every time an item is discontinued.
Which products are suitable?
- The price must be significantly lower than that of the main product. The add-on should feel like a small detail, not a new decision.
- The customer should be able to say yes without having to research anything. If the item requires consideration first, it belongs on its own product page.
- The choice of variants should be a matter of personal preference. Color and size work well. Phone models and other compatibility choices lead to returns rather than sales.
The “Bought Together” statistics page in the admin panel shows which of your products most often end up in the same order. This is the best place to find candidates, rather than guessing.
Works in these themes
Add-ons are a theme feature. The box is available in Delaware, DelawareDK, Montana, and MontanaB2B, and the variant selector works in all four. If you’re running a custom-built theme, your theme developer must first add the box to the product page.