Checkout.liquid is dead. Shopify retired it in 2026, and every store that was using checkout.liquid customizations or “Additional Scripts” in checkout has been migrated — or broken — by the change. Shopify checkout customization now happens entirely through Checkout Extensibility. Here’s what’s available by plan, what changed, and what the revenue impact of checkout optimization actually looks like.
70% of online shoppers abandon at checkout. The checkout is not a neutral handoff — it’s an active revenue lever.
Key Takeaways
- Checkout.liquid officially retired in 2026 — all stores now use Checkout Extensibility architecture
- Standard plans (Basic, Grow, Advanced): branding customization, app blocks, basic field controls
- Shopify Plus: UI Extensions (custom content blocks), Shopify Functions (custom discount/payment logic), full Branding API
- Shopify checkout customization upsell blocks on Plus average 10–15% AOV increase for stores that implement them correctly
What Changed in 2026: Checkout.liquid Retirement
If you had an older Shopify store with checkout customizations, this transition affected you directly.
Checkout.liquid Officially Retired: All Stores Migrated
Checkout.liquid was Shopify’s original mechanism for checkout customization — it allowed developers to modify the checkout’s HTML template. It was a Plus-exclusive feature, and many high-revenue merchants had built significant custom checkout logic into it.
Shopify announced the retirement years in advance. The migration deadline passed in 2024, and by 2026 checkout.liquid is no longer functional for any store. All Shopify checkout customization now goes through the Checkout Extensibility framework — a different architecture that uses React-based UI Extensions and Shopify Functions.
For merchants who had custom checkout.liquid implementations, this required rebuilding those customizations in the new framework. Some features available in checkout.liquid don’t have direct equivalents in Checkout Extensibility — they require architectural redesign.
”Additional Scripts” in Checkout: No Longer Functional
The “Additional Scripts” field in Shopify’s Settings → Checkout was a way to inject custom JavaScript into the checkout page — commonly used for tracking pixels (Meta Pixel, Google Analytics), custom validation, and third-party integrations.
This field is no longer functional. Scripts placed in “Additional Scripts” are not executed. If you had tracking scripts or custom logic there, they are not running.
Sarah didn’t realize her Meta Pixel had been placed in “Additional Scripts” in 2022 and never updated the placement. In January 2026, she wondered why her Meta ad attribution had been failing for months. The tracking was silent — no errors, just no data. She’d been running Meta ads without conversion data for an extended period.
If you had scripts in “Additional Scripts,” migrate them to Shopify’s Customer Events API immediately. This is where all tracking pixels and conversion scripts now belong.
February 2026: Background Image Restrictions Added
Shopify restricted background image customization in the checkout editor in February 2026. The Header and Main Content sections of the checkout no longer support custom background images.
This change affects stores that had used background images for brand expression in checkout. Available alternatives: background colors, brand colors, and logo placement remain fully customizable.
Shopify Checkout Customization on Standard Plans
Standard plans (Basic, Grow, Advanced) have meaningful Shopify checkout customization capability — just not unlimited capability.
Branding: Logo, Colors, Fonts, Button Styles Via the Checkout Editor
Go to Settings → Checkout → Customize checkout. The visual editor lets you configure:
- Logo: upload your store logo, set its size and position
- Banner image: available in some sections (post-February 2026 restrictions apply to specific areas)
- Colors: background color, accent color, button color, error color
- Typography: font selection from Shopify’s supported font library
- Button style: solid, outline, or shadow variations
These branding options make your checkout visually consistent with your store without requiring any code. For most standard stores, this level of customization is sufficient for brand coherence.
Basic Form Fields: Show/Hide Fields for Shipping Address
In the checkout editor, you can show or hide optional address fields (company name, apartment/suite, address line 2). This is straightforward field control, not custom logic.
Standard plans cannot: add custom fields to checkout (email opt-in at checkout, custom text inputs, custom question fields). Adding custom form fields requires Plus via UI Extensions.
App Blocks: Install Compatible Apps and Add Them to Checkout
Shopify’s App Store includes apps built on the Checkout Extensibility framework that are compatible with standard plans. These app blocks can be added to the checkout through the editor — they appear as widgets within the checkout flow.
App blocks on standard plans include: order summary additions, upsell offers (with limitations), trust badges, and loyalty point displays. The distinction versus Plus: these are pre-built app components, not custom-coded UI Extensions. They do what the app is built to do; they can’t be programmed to do something different.
Shopify Plus: Full Checkout Extensibility Unlocked
Plus gives you the full Checkout Extensibility toolkit for Shopify checkout customization.
UI Extensions: Custom Content Blocks, Banners, and Form Fields
UI Extensions let you build custom React-based components that render within the Shopify checkout. A developer can create: post-purchase upsell offers, in-checkout loyalty point balance displays, custom form fields (add-on purchases, personalization inputs, gift message fields), custom banners based on cart contents, and countdown timers for offers.
These are not off-the-shelf app blocks — they’re components your developer builds and deploys into the checkout. The flexibility is genuine: if you can describe the behavior and a developer can build a React component, it can exist in your checkout.
Shopify Functions: Custom Discount Logic, Shipping Logic, Payment Customization
Shopify Functions are serverless code (written in Rust, Go, JavaScript, or AssemblyScript) that run on Shopify’s infrastructure and modify core commerce behavior.
With Functions on Plus:
- Custom discount logic: apply discounts based on cart attributes Shopify’s native discount engine doesn’t support (buy X from collection A + Y from collection B = 20% off)
- Custom shipping logic: show or hide shipping rates based on cart contents, customer tags, or custom conditions
- Custom payment visibility: show or hide payment methods based on cart value, customer location, or order attributes
- Custom validation: prevent checkout completion based on custom rules (minimum order value per product category, required accompanying items)
Functions run in under 5 milliseconds on Shopify’s servers — they don’t add perceptible latency to checkout.
Branding API: Programmatic Checkout Appearance
The Branding API gives Plus merchants programmatic control over checkout appearance — not just the visual editor’s options. Custom CSS can be applied, checkout layout can be adjusted beyond what the editor provides, and brand expression can go significantly deeper.
Checkout Upsell Apps: Native Integration for AOV Optimization
On Plus, checkout upsell apps (Rebuy, AfterSell, and others) integrate directly into the checkout through UI Extensions. Post-purchase upsells — “Add this complementary product for $15” — appear after the customer’s credit card is charged but before the order confirmation. The customer can add the item with one click, no re-entry of payment information.
Marcus implemented a post-purchase upsell on his Plus store in Q1 2025. The upsell offer: “Add a leather care kit for $18?” displayed to every customer who purchased a leather good. Acceptance rate: 22%. At 150 orders/month: 33 additional $18 transactions = $594/month in additional revenue. Cost of implementation: $800 in developer time. Payback period: 6 weeks.
Revenue Impact of Shopify Checkout Customization
The capability is interesting. The revenue impact is the justification.
Checkout Upsell Apps on Plus: Average 10–15% Increase in AOV
This is a published industry benchmark from Shopify and third-party analytics from upsell app developers. A 10–15% AOV increase on a $3M/year store = $300,000–$450,000/year in additional revenue from the same number of orders.
The caveat: this assumes correct offer selection (relevant to the cart contents) and properly implemented UI that doesn’t create friction. Poorly designed upsells that feel like popups rather than value additions reduce conversion and can increase checkout abandonment.
Loyalty Point Display at Checkout: Reduces Churn for Subscription Stores
A UI Extension that displays a customer’s loyalty point balance — “You have 340 points worth $3.40 — earn 50 more points with this purchase” — reinforces loyalty program engagement at the moment of highest intent.
For subscription stores, this type of touchpoint reduces cancellation rates by reminding subscribers of accumulated value at the point of payment.
Custom Shipping Logic (Functions): Reduces “Why Is Shipping So Expensive?” Abandonment
A Shopify Function that shows free shipping for orders over $75 (when $75 has been reached in the cart) but hides the standard rate removes ambiguity. A “Free shipping — you qualified” message at checkout is a conversion signal that a static “Free shipping on orders over $75” banner in the header isn’t.
Abandoned checkout reasons: shipping cost surprises are consistently in the top 3. Custom shipping logic that clarifies or removes the surprise reduces this abandonment category.
Need Shopify checkout customization built correctly — with the implementation that drives the revenue lift, not just the capability enabled? See our Shopify development services → or explore our Shopify Solutions packages for checkout optimization.
Migration Path From checkout.liquid / Additional Scripts
If you had customizations in either of these, here’s the migration path.
What Was in Your checkout.liquid and What Now Replaces It
Common checkout.liquid customizations and their Checkout Extensibility equivalents:
- Custom branding/CSS → Branding API (Plus) or checkout editor settings
- Loyalty point display → UI Extension (Plus required)
- Order bump / upsell → Checkout upsell app block (Plus required)
- Custom form fields → UI Extension (Plus required)
- Custom JavaScript for tracking → Customer Events API (all plans)
Moving Tracking Scripts to Customer Events API
If you had Google Analytics, Meta Pixel, Google Ads conversion tracking, or any other tracking scripts in “Additional Scripts,” move them to the Customer Events API immediately.
In Shopify admin: Settings → Customer events → Add custom pixel. Paste your pixel/tracking code here. This is where all client-side tracking now runs — it’s executed within Shopify’s consent management framework and is properly sandboxed.
This affects all plans, not just Plus. If you installed your tracking scripts in “Additional Scripts” and haven’t verified they’re still firing, verify today.
Conclusion
Shopify checkout customization in 2026 is a two-tier system. Standard plans provide branding control (logo, colors, fonts) and pre-built app blocks. Plus provides the full Checkout Extensibility toolkit — custom UI Extensions, Shopify Functions, and the Branding API — that enables revenue-moving customizations like checkout upsells, custom form fields, and dynamic shipping logic.
The checkout.liquid retirement and “Additional Scripts” deprecation are done. If you haven’t migrated your tracking scripts to the Customer Events API, do it today — you’re running with broken analytics.
For stores on Plus considering checkout customization investments: the 10–15% AOV lift from well-implemented checkout upsells is the primary ROI driver. On $1M+ GMV, a 12% AOV improvement = $120,000+/year. The implementation cost is typically $1,500–$5,000 for a well-built upsell extension. Payback is measured in weeks, not months.
For standard plan stores: ensure your checkout branding is configured, your tracking is in the Customer Events API (not “Additional Scripts”), and your checkout flow is mobile-tested. The Plus features are real, but the standard plan foundation needs to be solid first.
For custom Shopify checkout customization — upsell extensions, Functions, or tracking migration — our Shopify Solutions packages deliver the technical build with conversion-focused design.
Frequently Asked Questions
Can I customize Shopify checkout without Plus?
Yes, with limitations. Standard plans offer branding customization (logo, colors, fonts) via the checkout editor and the ability to add pre-built app blocks. What requires Plus for deeper Shopify checkout customization: custom UI Extensions (custom content blocks, custom form fields), Shopify Functions (custom discount/shipping/payment logic), and the Branding API for programmatic appearance control.
What is Shopify Checkout Extensibility?
Checkout Extensibility is Shopify’s framework for checkout customization, replacing the retired checkout.liquid system. It consists of two components: UI Extensions (React-based components rendered within the checkout, available on Plus) and Shopify Functions (serverless code that modifies core commerce behavior like discounts and shipping). Standard plans can access pre-built app blocks built on UI Extensions; full custom Extensions require Plus.
What happened to checkout.liquid?
Checkout.liquid was Shopify’s previous Plus-exclusive mechanism for checkout HTML customization. Shopify retired it in 2024 and fully removed it by 2026. All stores that had checkout.liquid customizations were required to migrate to the Checkout Extensibility framework. The migration was not automatic — stores with custom checkout.liquid implementations needed developer work to rebuild their customizations in the new architecture.
Can I add upsells to Shopify checkout without Plus?
Third-party apps with pre-built upsell blocks can be added to standard plan checkouts through the checkout editor. These are less customizable than Plus UI Extensions — they do what the app is built to do, with limited flexibility. Post-purchase upsells (appearing after payment, before order confirmation) typically require Plus for the seamless one-click add-to-order functionality that generates the 10–15% AOV lift benchmark.
Does Shopify checkout customization affect conversion rates?
Yes. Checkout abandonment is 70%+ for most stores. The factors within checkout that affect conversion: speed (slow checkout pages increase abandonment), trust signals (security badges, reviews), clarity of shipping costs (surprises at checkout are a top abandonment reason), and friction in the form completion process. Custom checkout features — upsells, loyalty displays, dynamic shipping — affect AOV more than raw conversion rate. Reducing checkout friction improves raw conversion; upsells improve order value from completed transactions.