Product upsell

What it is

The upsell block sits after the last item in the cart drawer. Each card shows a product image, its name, its price, an option picker when the product has more than one option, and an Add button.

You choose where the products come from. Either you pick them yourself, or you let Shopify's own recommendations do it.

When to use it

• You sell obvious companions — a lens with a camera, a case with a phone.
• You want one collection (say “Add-ons” or “Best sellers”) offered in every cart.
• You have no idea what pairs with what, and want Shopify to decide from your own sales data.

Set it up

1. Open your cart in the Cart builder.
2. In Add a module, choose Product upsell and press Add.
3. Find the new row in the Modules list and press Settings.
4. Set Where products come from.
5. If you chose Products I choose, press Choose from your catalogue under Products to offer and pick them. If you chose A collection, do the same under Collection to draw from. If you chose Shopify's recommendations, there is nothing to pick.
6. Optionally set How many to show, a minimum price, and any products you never want offered.
7. Press Save.
8. Go back to the cart builder and press Review and publish. Nothing you changed reaches a shopper until you publish.

Settings

How products are chosen

Your choice always beats the algorithm. The drawer checks, in order:

1. Your products or your collection, if you set a source and it produced anything. Shopify is never asked in this case.
2. Shopify's “complementary” products for the most valuable item in the cart. These only exist if you have set them up in Shopify's Search & Discovery app, so for most stores this is empty.
3. Shopify's “related” products for that same item. This is what most stores end up showing.

The list is anchored on the highest-value line in the cart, not the most recently added one. Recommending off a cheap impulse buy tends to recommend more cheap impulse buys.

What is never offered

• Anything already in the cart.
• Anything on your Never offer these list.
• Anything below your minimum price.
• Anything with no variant in stock.
• Anything excluded from your reward thresholds. The upsell reuses the exclusion list from the rewards bar rather than asking you for a second one.

When you pick products yourself or name a collection, a few more are dropped while publishing: draft products, products not published to your online store, products that are entirely out of stock, and products with more than ten variants (one drop-down cannot honestly hold more).

What a shopper sees

• The heading reads You might also like. You can change it, and the button wording, on the Shopper copy screen.
• The price shown is the cheapest variant that is actually buyable, and the product name links to its page.
• A product with more than one available variant gets a drop-down. Add stays greyed out until an option is chosen. Sold-out variants are listed but cannot be selected, so nobody hunts for a size that does not exist.
• After a successful add the button reads Added, the card fades, and it removes itself two seconds later.
• If the add fails, the button quietly goes back to Add. No error is shown — the shopper's own cart is more important than an upsell that did not work.
• Adds made here are tagged on the cart line, so the app can tell an upsell add from a normal one.

How it behaves in the drawer

• It loads after the rest of the drawer has painted, with its height reserved first, so the shopper's own items never jump.
• The block is capped at roughly 30% of the drawer height and scrolls inside that cap. Nothing is clipped out of reach.
• The list is only recalculated when the most valuable item in the cart changes. Changing a quantity elsewhere will not reshuffle the cards under the shopper's finger.
• If there is nothing left to show — every candidate filtered out, or the request to Shopify failed or timed out — the whole block disappears. It never pads itself with a filler product and never shows an empty box.

Limitations

Things a merchant reasonably expects that this module does not do today.

• Your products are frozen at publish time. Hand-picked products and collection products are looked up when you publish and stored with the cart. Add a product to that collection afterwards and it will not be offered until you publish again. Nothing in the admin warns you that the list has gone out of date.
• A collection is sampled, not used whole. At most eight products are taken from it, and the same eight are shown to everyone. It does not rotate, randomise or personalise per shopper.
• More than eight hand-picked products are ignored. Only the first eight in your list are ever used.
• An empty result falls back silently. If you choose Products I choose or A collection and nothing survives publishing — empty list, everything out of stock, everything filtered — the drawer shows Shopify's recommendations instead. It does not go blank, and it does not tell you.
• You are not told what was dropped. The app records why each product was skipped while publishing (not active, not published, out of stock, too many variants) and then does not show you those reasons anywhere.
• The preview does not use your chosen products. The Preview screen falls back to Shopify's recommendations for this module, so it is not a reliable check of a hand-picked or collection source. Check it on the live storefront after publishing.
• A stale warning may appear in the cart builder. The builder can show “This rule doesn't match any products right now. Shoppers won't see the upsell.” even after you have configured the module correctly. The warning is checking the wrong thing. If your settings are saved and published, the module works — ignore this banner.
• The minimum price is not converted per market. It is compared against the price the shopper sees. On a store selling in more than one currency, the floor will filter differently abroad than at home.
• No bundle pricing and no upsell-only discount. Products are added at their normal price. There is no “add all” button, no quantity picker on the card, and no star ratings or review counts.
• No per-product rules. You cannot say “offer the lens only when a camera is in the cart”. Display rules control whether the whole module shows, not which product is offered.