Introduction to Checkout Extensions

Checkout extensions let you keep selling and rewarding shoppers on Shopify's native checkout page - after the cart, where intent is highest. You build each one in EliteCart and place it in Shopify's checkout editor.

The three extensions

Extension

What it does

Checkout Upsells	A product‑recommendation block you can place anywhere in checkout (order summary, information step, or shipping). Add several, each in a different spot.
Line Item Upsells	A small button on every cart line in checkout. Tapping it opens a popover with pairing recommendations for that product.
Checkout Reward Bar	Your shipping and reward progress bar — including gift unlocking — shown inside checkout. Reuses the rewards from Cart designer.
Checkout Add-on	An optional add-on product shown as a compact card with a checkbox. Place it anywhere in checkout; shoppers tick it to add the item before they pay.

Requirements

• Shopify Plus — checkout extensions only run on Plus stores.
• EliteCart Professional plan or higher.
• The Checkout Reward Bar also needs Rewards V2 set up in Cart designer.

How it works

Every checkout extension follows the same two‑step pattern:

1. Build it in EliteCart. Go to Checkout in the left navigation and click Create module. Pick Upsell block, Line item upsells, Reward bar, or Add-on, then configure it.
2. Place it in Shopify. Open the Shopify checkout editor (in Shopify admin: Settings → Checkout → Customize, or use the Open checkout editor button shown on the module page) and add the matching block to your checkout layout.

The Checkout Upsells and Add-on modules give you a Module ID. Copy it and paste it into the matching block's settings in the checkout editor — this is how a block knows which module to show. The Line item upsells and Reward bar modules have no Module ID: there is only one of each per store, so the checkout editor finds them automatically once you enable the slot or add the block.

Each module page shows a live status banner telling you whether its block is placed in checkout yet, so you always know if the final step is done.

Set up your first module

1. Open Checkout in EliteCart and click Create module.
2. Choose a module type and configure it (see the article for that extension).
3. Click Save.
4. Click Open checkout editor, add or enable the matching block, and - for Checkout Upsells and Add-on - paste the Module ID.