If you have ever bought a phone and been offered a case at the same moment, you have seen a product add-on. On Shopify, an add-on is a small extra shown on the product page so the shopper can pick it up without leaving.

What is a product add-on?

A product add-on is an optional item that goes with the main product. Think of a screen protector next to a phone case, a ribbon and a card next to a bouquet, or paper filters next to a bag of coffee beans.

Two things set it apart from other kinds of offers:

• It sits on the product page. The shopper sees it while deciding, not later.
• It is separate from the main product. Each add-on is its own product with its own price and stock, so your inventory stays accurate.

Why add-ons raise average order value

Average order value (AOV) is total revenue divided by the number of orders. If a store makes $5,000 from 100 orders, AOV is $50. If a third of shoppers add a $9 extra, revenue from the same 100 orders goes up by about $300, and AOV rises to $53. No new traffic was needed.

That is the whole appeal: you earn more from visitors you already paid to get. The numbers above are an example of the arithmetic, not a promise of results. What you gain depends on your products and how well the extras fit.

What makes a good add-on?

The best add-ons are cheap compared with the main product, obviously related to it, and easy to understand in a glance.

1. Price. An extra at 10 to 30 percent of the main price feels like a small decision.
2. Relevance. If the shopper would ask "why is this here?", remove it.
3. Low effort. No new choices, no sizing, no extra page.
4. Real stock. Hide extras that are sold out so nobody is disappointed.

Where should add-ons appear?

Right under the buy area of the product page works well, because that is where the decision happens. Pop-ups work against this: they interrupt the page. We compare the two in upsell pop-ups vs on-page add-ons.

How do you add them to a store?

You can build it by hand in your theme, but it gets complicated fast: variants, quantities, stock and the cart all need to work together. An app does that for you. Our step-by-step guide shows how to add product add-ons to a Shopify product page without code.

Key takeaways

• An add-on is a related extra, shown on the product page, added in one click.
• It raises AOV by selling more per order from the traffic you already have.
• Keep it relevant, cheap, and limited to a few choices.

There are four common ways to sell more to someone who is already buying. They are not equal, and the right one depends on how much you want to interrupt the shopper.

The four approaches at a glance

What is wrong with pop-ups?

Nothing is wrong with them in every case, but they have a built-in cost. A window that opens over the page stops the shopper mid-decision. They have to read it, judge it and close it before they can continue. On mobile, where screens are small, that cost is higher.

If you use them, show them rarely and make them easy to close.

When do post-purchase offers make sense?

After checkout the sale is safe, so an extra offer cannot lose the order. The limit is that the shopper has already left the browsing mindset, and you can usually show only one offer at a time.

When are bundles the better fit?

Bundles suit products that are really sold as a set, like a skincare routine. They are less flexible when shoppers want to pick only part of the set.

Why on-page add-ons suit most stores

With add-ons on the product page, the shopper sees the extras as part of the same decision, picks the ones they want, and chooses quantities. There is no new window and no page change. This is the approach QuickAddons is built around. If you are new to the idea, start with what Shopify product add-ons are.

How to choose

1. If your products naturally come with accessories, start with on-page add-ons.
2. If you sell sets, add a bundle for those products only.
3. If you want an extra layer, add one post-purchase offer.
4. Use pop-ups last, and watch your conversion rate after turning them on.

Whatever you pick, change one thing at a time so you can tell what worked.

You can have add-ons showing on a product page in a few minutes. Here is the full path, using QuickAddons.

Before you start

You need a Shopify store and the products you want to offer as extras already created in your catalog. If you are still deciding what to offer, read what makes a good add-on first.

Step 1: Install the app

Open the QuickAddons listing on the Shopify App Store and install it. The 14-day free trial starts without a credit card.

Step 2: Choose your add-ons

In the app, create an add-ons group and pick products from your catalog. A group is a reusable set, so you build it once and use it in many places. Aim for three to five items that clearly belong with the main product.

Step 3: Decide where they show

Assign the group in whichever way fits:

• One product, for a specific pairing like a case for a phone.
• A collection, when a whole category shares the same extras.
• Every product, as a store-wide default.

You can override the default on any product that needs something different.

Step 4: Turn on the widget in your theme

On an Online Store 2.0 theme, open the theme editor, go to a product page, add the QuickAddons app block under the buy buttons, and save. No code is involved.

On an older or custom theme, open the Settings page in the app, copy the snippet, and paste it into your product template. The page walks you through it.

Step 5: Match your store's look

Set colors, fonts, button text and card style so the widget feels like part of your theme. The text is yours, so you can write it in any language.

Step 6: Test it like a customer

Open a product page, add an extra, and check that it lands in the cart with the main product and the right price. Test on a phone too. Then check that sold-out extras behave the way you want, since QuickAddons can hide them or show them as unavailable.

What to watch after launch

Give it a week or two, then look at how many orders include an extra. The Pro plan has an analytics dashboard with add-on revenue and conversion. If one extra never sells, swap it for something more relevant.

For a comparison with other upsell styles, see upsell pop-ups vs on-page add-ons.