Checkbox Upsell uses a checkout app block and requires Shopify Plus.
You need permission to edit and save the published checkout profile.
Choose one active product that is available in each selected market.
Open Apps > Order Editing > Upsells.
Select Create strategy and open Templates.
Choose Checkbox Add-On. This template selects the Checkbox Upsell placement and preloads a Single Product module.
Choose the Shopify markets that can see the offer.
Select the one product customers can add.
Add concise offer copy and any required customer targeting.
Keep the strategy in Draft, preview it, and save.
Checkbox Upsell renders one optional product. A dynamic or multi-product module is not the recommended path for this placement.
Open the Checkbox Upsell setup action in Order Editing.
Continue to Shopify's Checkout Editor.
Select Add app block where the offer should appear and choose Checkbox Upsell.
Place it near the relevant shipping or payment step without competing with the order summary.
Choose whether the block shows product details and its card border.
Save the checkout profile.
Use a locked strategy when this exact block must request this exact offer.
In the strategy, enable Only show this strategy when an app block requests it by ID.
Copy the strategy ID.
In Shopify's Checkout Editor, open the Checkbox Upsell block.
Paste the ID into Locked Strategy and save.
The strategy is then excluded from normal matching and does not appear anywhere else unless another supported app block requests the same ID.
Activate the strategy when its product, targeting, and market are ready.
Add a qualifying product to the cart and continue to checkout without placing an order.
Confirm the checkbox is initially unticked.
Tick it and confirm the offered product is added without leaving or reloading checkout.
Untick it and confirm the product is removed and totals update.
Repeat with a cart that should not match the strategy.
