Shopify Checkout Extensions:
The Complete 2026 Guide
Shopify Scripts are deprecated. Checkout Extensions are the new standard. Here's everything merchants need to know — no developer required to read this guide.
Old vs. New: What Changed in 2026
What Are Shopify Checkout Extensions?
Checkout Extensions are Shopify's official framework for customising the checkout page. They work as React-based UI components that slot into predefined "extension points" within the Shopify checkout — before, during, and after the payment flow.
Unlike the old Script Editor, extensions run in a sandboxed environment on Shopify's own infrastructure. They're faster, more secure, and won't break when Shopify updates checkout. They're also the only way Shopify allows third-party apps to touch checkout in 2026.
Shopify Functions: The Logic Layer
Shopify Functions handle the business logic behind checkout customisations. Where Checkout Extensions control what customers see, Functions control what happens:
- Discount Functions: Create custom discount rules more complex than native discounts allow (e.g. tiered B2B pricing, bundle discounts, conditional offers).
- Payment Customisation Functions: Show or hide payment methods based on cart contents, customer tags, or order value.
- Delivery Customisation Functions: Rename, sort, or hide shipping options based on products in cart.
- Cart Transform Functions: Modify cart line items before checkout — used for bundling and quantity constraints.
What Can You Do at Checkout With Extensions?
Show 1–2 complementary product offers directly in checkout — before the customer places the order. Takes one click to add. No new cart required.
Show review counts, security badges, or guarantee copy inside checkout to reduce abandonment.
Add custom text fields for gift messages, delivery instructions, or business PO numbers.
Display estimated delivery dates, carrier information, or threshold messages ('Order in next 2hrs for same-day dispatch').
Build complex discount UIs — loyalty point redemption, referral codes, B2B negotiated pricing — that go beyond Shopify's native discount box.
Offer a subscribe-and-save option within checkout that converts one-time buyers to subscribers without leaving the page.
What Requires Shopify Plus?
How to Add Upsells to Shopify Checkout (No Code)
For most merchants, the best way to add checkout upsells without writing code is to install a Shopify-certified app built on Checkout Extensions. Here's what to look for:
- Built on Shopify Functions, not scripts — If the app's listing mentions "Script Editor" or "checkout.liquid", it's deprecated technology.
- Native checkout integration — The offer should appear inside the checkout page, not as a pop-up overlay (which Shopify restricts).
- AI-powered targeting — Apps that show the same product to everyone convert at 2–4%. Apps that match the offer to the specific cart contents convert at 10–20%.
- Dashboard & analytics — You should be able to see take-rates, revenue impact, and test different offers per product category.
Cognify Suite is built natively on Shopify Functions and Checkout Extensions. It passes Shopify's certification requirements, runs without scripts, and uses AI to match the checkout offer to the actual products in the cart — not a manual rule. See how the AI works →
Add AI checkout upsells — no code, fully compliant
Cognify Suite adds AI-powered upsell blocks directly inside Shopify checkout. Built on Shopify Functions, certified by Shopify, and takes 5 minutes to set up.
Frequently Asked Questions
Written by Cognify Growth Team — Last updated: