Custom checkout solutions: integrating Shopify Functions for a unique shopping experience


Chris Rausch


September 18, 2023

If you’re not a developer, the idea of accessing the backend of your Shopify store can be intimidating. However, the development of Shopify Functions means it’s easier than ever to customize your checkout - and you can access information that helps you build unique experiences without ever seeing a line of code.

Ready to see how installing an app can unlock so much of your store’s potential? Keep reading.

The benefits of Shopify Functions vs Shopify Scripts

shopify functions code

Shopify Functions is a relatively new development that was announced by Shopify in 2022 as a part of the Checkout Extensibility upgrade. It was developed as a result of Shopify’s efforts to make it simpler to customize your checkout page so that you can do more to build an effective checkout experience.

Checkout Extensibility upgraded the previous checkout.liquid checkout framework with modular apps, code-free customization, upgradability, future-proofing, and, of course, Shopify Functions, which replaced its predecessor, Shopify Scripts.

Shopify Scripts allowed for code-based interaction with the various elements of your checkout to make customizations to things like checkout fields, discounts, page elements, and more. However, you had to enter code directly into the interface to use it, creating a security flaw that made it easy for something to get broken during the code transfer or accidentally when making changes. If something went wrong, it directly impacted the checkout process (along with checkout.liquid) and could take your checkout down entirely.

Customizations made with Shopify Scripts are all contained within an app that can be installed or removed as necessary without any coding experience required or risk of a mistake during transfer. 

Apps can also be individually updated to add new features or fix bugs without impacting the rest of your checkout page to help avoid catastrophic errors. 

Even better - each app can use its own interface and directly integrate with Shopify’s existing admin sections to make it easy to implement your customizations.

Finally, Shopify Functions are available to all businesses - not just Shopify Plus stores - increasing the market for developers and making it easier for any business to find the right app to elevate your checkout process.

How Shopify checkout functions extends your checkout

Shopify Functions lets you access elements of the backend of the checkout process so that you can use the unlocked information to take control of how your checkout works. Customer, cart, checkout, and product information are all accessible and can be edited to build complex functions that you won’t find out-of-the-box from Shopify.

Here are a few ways that Shopify Functions expand your checkout capabilities.

Highly-customizable discounts

If you’ve ever wanted to offer unique and customizable bundles, quantity incentives, or value-based discounts that are more than just a banner at the top of your site or sale prices on items, Shopify Functions can help.

You can access information like the cart total, the specific product in the cart, the number of products, and multiple other data points based on what your customer is looking to buy. Using this information, you can use an app that allows you to create discounts by accessing that information, applying a discount, and returning it to checkout so that the discount takes effect for purchase.

$10 off orders of $100 and “buy 3, get 10% off” are two examples of custom discounts you can create with Shopify Functions.

Control over shipping methods

Do you offer delivery? Local delivery options can be a great way to increase business and offer a more unique experience. However, if you only want locals to be able to receive deliveries, you need to customize who receives it as a shipping option.

Using Shopify Functions, you’re able to check information like the customer’s shipping or billing addresses at checkout to see if they’re close enough for you to deliver. You can set your own range and only offer it to addresses within that range without causing confusion from customers who are further away.

Customizing payment method requirements

Shopify Functions also lets you control which payment methods are offered at checkout to ensure you’re offering valid options for customers to use.

You can use the customer’s location or order total to determine whether cash payments are available for hand-delivery. Shopify Functions also lets you change which countries receive a certain payment method so you can ensure favorable international rates on purchases.

Cart and checkout validation

Validating the contents of your cart or the information entered during checkout allows you to control who is able to complete checkout. Quantities, products in the cart, cart totals, and other factors can be isolated to require validation.

You could limit product purchases to a certain number to help avoid items selling out to scalpers, create a maximum cart value for new accounts to prevent fraud, or implement an age requirement to complete a purchase so that you’re protected at all times.

Other Shopify custom checkout upgrades to make

shopify functions customizations

You can also make other changes in addition to those currently offered by Shopify Functions. WIth the right apps, you can totally take control over checkout and add valuable features that help your business thrive.

Checkout Extensions Plus

Checkout Extensions Plus is an app that leverages Checkout Extensibility’s increased customization potential so that you can customize the visual elements of checkout as well as the backend. Colors, styles, banners, images, and checkout fields are just a few pieces of checkout that can be changed to your branding so that you provide a consistent experience from start to finish and increase conversion rates.


UpsellPlus expands on the discount logic that can be applied using Shopify Functions. With the app, you can create upsells and cross-sells that provide offers to your customers so that you can convince them to spend more. BOGO, bundle discounts, product upgrades, and warranties are some examples of upsells and cross-sells that can help you increase your average order value so that you can grow revenue.

Take advantage of Checkout Extensibility and Shopify Functions for the optimal checkout

Customization is an essential element of a successful checkout process. From visual elements to backend logic, the more you can customize, the better you can tailor the experience to customers’ wants and needs.

Give UpsellPlus and Checkout Extensions Plus a try to unlock seamless, code-free customizations that let you do more with less so that your business can thrive.

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