Pre ticked box to allow substitute products

Shopify Discussion

Topic summary

A merchant wants to add a pre-ticked checkbox on the cart page allowing customers to consent to product substitutions when items are out of stock. The goal is to communicate this preference to warehouse pickers during fulfillment.

Suggested Solutions:

  • Prevent overselling: Disable the option to purchase out-of-stock items and use apps like “Alternative, Related Products” to suggest alternatives at checkout
  • Order notes: Enable Shopify’s built-in order notes feature to collect customer preferences
  • Cart attributes: Implement custom cart attributes through code (requires HTML/CSS/JavaScript/Liquid knowledge) or use apps from the Shopify App Store
  • Substitutions app: A newly launched app that manages SKU swaps for out-of-stock items, which can be combined with cart attributes to capture customer consent

The discussion remains open with multiple technical approaches offered, though implementation would require either coding expertise or hiring a Shopify Expert.

Summarized with AI on October 27. AI used: claude-sonnet-4-5-20250929.
1

Hi,

We would like to have a pre ticked box at the cart page for allowing substitute products if any of the products ordered are out of stock.
Can you guide us how will we be able to carry forward that functionality further so that the pickers on ground level will get to know whether that customer has ticked or unticked.

2

Hi @Love2shop ,

That’s a great question.

To provide the best guidance possible, let me better understand the situation. Do you intentionally allow overselling out-of-stock products, and in what scenario?

If not, you can always untick this option for any existing products. That way, a customer won’t be able to order sold out products in the first place. But when that happens, you can offer a related product of interest to them and capture that sale using an app called Alternative, Related Products.

Most Shopify themes allow you to enable ‘order notes’ so you can collect extra details from customers for each order they place. Here’s a page on Shopify’s help docs with more details.

If you’re comfortable editing code, here’s a forum link for a tutorial on adding cart attributes to your store’s theme. This is an advanced tutorial, and knowledge of HTML, CSS, JavaScript, and Liquid is required. Consider hiring a Shopify Expert if you aren’t comfortable doing the steps in the tutorial.

Finally, you can check out some apps on the App Store that have a built-in feature for cart attributes. Find the complete list of available apps here.

I hope this helps!

3

Hey!

That’s a great idea—especially if your team is doing local fulfillment.

We just launched an app called Substitutions that lets you define which SKUs can automatically swap in when something goes out of stock.

While the app doesn’t include a pre-ticked box at checkout by default, you can add that using Shopify’s cart attributes and tie it to order tags or notes for your team to reference.

Let me know if you want to explore that setup.

—Ahmed from Substitutions