Shopify Checkout Optimisation [2026]

The checkout is the most critical point of your Shopify store. 70% of all cart abandonments happen here. And at the same time, the checkout is the area most Shopify merchants optimise the least — because they believe Shopify's standard checkout can't be customised.

That's no longer true. Since Shopify Checkout Extensibility (2023) and continuous improvements through to 2026, you have more control over the checkout than ever before. In this guide, we show you what's technically possible — and what makes economic sense.

The Checkout Landscape in Shopify 2026

What has changed

Previously (pre-2023), the Shopify checkout was a black box. You could change the logo and colours — that was it. Plus merchants had slightly more options via checkout.liquid, but that was unstable and has not been supported since 2024.

Today you have three levers at your disposal:

1. Checkout UI Extensions React-based components that you can insert at defined positions in the checkout. Technically: Web Components running in a sandbox.

2. Shopify Functions Server-side logic that changes checkout behaviour: discounts, shipping rates, payment methods, cart transforms. No UI, just logic.

3. Checkout Branding API Visual customisations via the API: colours, fonts, corner radius, spacing. No code in the checkout, just configuration.

Checkout UI Extensions: What, Where and How

The Extension Points

Shopify defines specific positions in the checkout where you can add UI. As of 2026, there are over 20 extension points. The most important ones:

Before the checkout:

purchase.checkout.block.render — Custom blocks in the checkout body
purchase.checkout.header.render-after — After the header
purchase.checkout.footer.render-before — Before the footer

During the checkout:

purchase.checkout.contact.render-after — After contact details
purchase.checkout.shipping-option-list.render-after — After shipping options
purchase.checkout.payment-method-list.render-before — Before payment methods

After the checkout:

purchase.thank-you.block.render — On the thank-you page
purchase.thank-you.customer-information.render-after — After customer information

Practical Use Cases

Use Case 1: Trust Badges Trust signals directly in the checkout: SSL badge, money-back guarantee, customer reviews. Sounds simple, but has measurable impact: 5-15% conversion uplift in our tests.

Use Case 2: Upselling in the Checkout Offering an additional product before the customer pays. Must be subtle — no pop-up, but an elegant recommendation. Shopify's Order Status Page is the perfect place for post-purchase upsells.

Use Case 3: Custom Fields Gift message, preferred delivery date, company name for B2B. Stored via Line Item Properties or Metafields and visible in the order.

Use Case 4: Delivery Date Picker Customers choose their preferred delivery date. Especially relevant for food, flowers, gift shops. The extension communicates with your shipping logic.

Shopify Functions: Checkout Logic Without UI

Shopify Functions are server-side programs that run in WebAssembly (Wasm). They change checkout behaviour without rendering a UI.

The Function Types

Discount Functions

product_discounts — Automatic discounts based on products in the cart
order_discounts — Discounts on the entire order
delivery_customizations — Shipping cost logic

Cart Transform Functions

Bundle products together
Automatically add gift items
Adjust prices based on customer group (B2B)

Payment Customization Functions

Show/hide payment methods based on order value
Filter payment methods by country/region
Rename or reorder payment methods

Delivery Customization Functions

Filter shipping options based on products
Dynamically calculate shipping costs
Express shipping only above a certain order value

Practical Example: B2B Pricing with Functions

In our project with Bekateq, we used Cart Transform Functions to implement customer-specific pricing. The flow:

Customer logs in (B2B Account)
Custom Metaobject contains individual prices per product
Cart Transform Function reads the Metaobject and adjusts prices
Checkout displays correct B2B prices

80 lines of code. No app. No monthly costs. That's the architecture decision that makes the difference.

Conversion Optimisation: What Actually Works

Technology alone isn't enough. Here are the checkout optimisations that have the greatest impact in our experience:

1. Prominently offer guest checkout

40% of abandonments happen because customers don't want to create an account. Guest checkout must be the default option, not hidden behind "Create account".

Implementation: Checkout settings in Shopify Admin → "Customer accounts" set to "Accounts are optional".

2. Optimise payment methods

In Germany 2026: PayPal, Klarna, Apple Pay, Google Pay, credit card, invoice (B2B). In this order of popularity. If you only offer credit card and PayPal, you're losing customers.

Implementation: Shopify Payments + all relevant payment gateways activated. Order controlled via the Checkout Branding API.

3. Make shipping costs transparent

"Shipping costs will be calculated in the next step" is a conversion killer. Show shipping costs as early as possible — ideally already on the product page or in the cart.

Implementation: Shopify's Cart Shipping Calculator or Custom Shipping Estimator as a section.

4. Express checkout without checkout

Shop Pay, Apple Pay and Google Pay offer express checkout directly from the product page. This skips the entire checkout process. Impact: 15-30% higher conversion on mobile.

Implementation: Activate Dynamic Checkout Buttons in product templates. Use Shopify's payment_button Liquid tag.

5. Progress indicator

Customers want to know how many steps are left. A clear progress indicator reduces perceived complexity.

Implementation: Checkout Branding API. Shopify offers a native progress indicator that is configurable.

Checkout Branding API: Visual Fine-Tuning

The Checkout Branding API allows you to customise the visual appearance of the checkout — without code in the checkout itself:

What you can customise:

Corner radius (global or per element)
Typography (font, size, weight for headings and body)
Colours (primary, secondary, background, text)
Spacing (padding, margin)
Form field styling
Button styling

Limitations:

No free CSS
No JavaScript
No structural changes (step order)
No removal of native elements

Best Practice: Keep the branding as close to your storefront as possible. A consistent design experience from product page to checkout reduces abandonment rates.

Common Mistakes in Checkout Optimisation

Mistake 1: Too many upsells in the checkout

One upsell is fine. Three are pushy. The checkout is not the place for aggressive sales strategies.

Mistake 2: Custom fields without validation

If you add custom fields in the checkout (e.g. company name), validate the input. Empty required fields or incorrect formats lead to frustrated customers and invalid orders.

Mistake 3: Apps instead of Functions

Many stores use apps for things Shopify Functions can handle. An app for automatic discounts costs €20-50/month and loads JavaScript. A Function costs nothing and has no performance impact.

Mistake 4: Checkout.liquid (Legacy)

If your store still uses checkout.liquid: migrate. Shopify is discontinuing support. Checkout Extensions are the future. In our Architecture+ Service, we guide migrations.

Measurement: How to Track Checkout Optimisations

Key Metrics

Cart-to-Checkout Rate: How many cart visitors start the checkout? (Target: >50%)
Checkout Completion Rate: How many checkout starters buy? (Target: >60%)
Payment Method Distribution: Which payment methods are used?
Checkout Step Drop-off: At which step are you losing customers?

Tools

Shopify Analytics (native, basic metrics)
Google Analytics 4 (Enhanced E-Commerce Tracking)
Hotjar/Microsoft Clarity (heatmaps in checkout — note: GDPR)

What we implement at smplx.

Checkout optimisation is part of our Architecture+ Service and our Technical Audit.

In the audit we check:

Which checkout extensions are active
Whether legacy checkout.liquid is still in use
Performance impact of checkout apps
Payment method configuration
Branding consistency

In the Architecture+ project we implement:

Checkout UI Extensions for upsells, trust badges, custom fields
Shopify Functions for pricing logic, shipping logic, payment logic
Checkout branding for visual fine-tuning
Tracking setup for conversion measurement

Conclusion

The Shopify checkout is no longer an immutable system. With Extensions, Functions and the Branding API, you have more control than ever before. But: technology without strategy is worthless. Don't optimise blindly — optimise based on data.

The biggest quick wins: guest checkout as default, all relevant payment methods, express checkout buttons, transparent shipping costs. That alone can mean 10-20% more conversions.

For everything beyond that, you need a technical architecture that cleanly integrates custom Extensions and Functions. That's our job.