Shopify checkout extensions are the app-based way to change Shopify’s checkout: apps add blocks to checkout pages, run business logic with Shopify Functions, and track events with web pixels, all configured in the checkout editor instead of code. They replaced checkout.liquid, which no longer works on the information, shipping and payment steps.
What you can use depends on your plan. Every plan from Basic up can add app blocks to the Thank you and Order status pages, while blocks on the information, shipping and payment steps need Shopify Plus. Each highlighted area of checkout holds at most 3 apps, and only one app can run the post-purchase page at a time. Two deadlines closed in 2026: Shopify Scripts stopped running on June 30, 2026, and non-Plus stores had until August 26, 2026 to upgrade their Thank you and Order status pages.
- Basic, Grow or Advanced: customize the Thank you and Order status pages and the post-purchase page.
- Shopify Plus: customize every checkout step, plus custom apps built with Shopify Functions.
- Still on old scripts? Run the upgrade guide in Settings > Checkout.
This article covers what the four extension types are, what each plan allows, why Shopify made the switch, how to add an extension step by step, how to use extensions for upsells, and how to fix the problems merchants hit most.
What are Shopify checkout extensions?
Shopify checkout extensions are pieces of an app that plug into checkout at points Shopify defines, so the checkout stays fast and upgrade-safe. Shopify’s developer documentation groups them into four types: checkout UI extensions, Shopify Functions, web pixel extensions and post-purchase extensions. “Extension” here means an app component, not a browser extension.
Checkout UI extensions
Checkout UI extensions are the visible blocks: banners, custom fields such as a gift note, product offers, surveys, trust messages and delivery instructions. A merchant places them in the checkout editor. Shopify’s reference states that up to three extensions can sit in the same block location, each compiled extension must stay under 64 KB, and extensions run in a sandbox with no access to payment data or the checkout HTML (Shopify checkout UI extensions reference).
Shopify Functions
Shopify Functions are server-side logic with no visible block. They power custom discounts, payment and delivery customizations, cart validation and bundles. Functions are the official replacement for Shopify Scripts. Public apps that use Functions work on every plan; custom apps built with Functions need Shopify Plus.
Web pixel extensions
Web pixel extensions are tracking code that runs in a sandbox and listens to customer events such as checkout started and purchase. They replace the old “additional scripts” box for tracking tags.
Post-purchase extensions
Post-purchase extensions show a page between payment and the Thank you page, usually with a one-click offer. Only one app at a time can control this page.
Which checkout extensions work on your Shopify plan?
Your plan decides where extensions can appear: Basic and higher plans get the Thank you, Order status, customer account and post-purchase pages, and Shopify Plus adds the information, shipping and payment steps. The table summarizes Shopify’s Help Center page on checkout apps (Customizing your checkout with apps).
| Checkout area | Basic, Grow, Advanced | Shopify Plus |
|---|---|---|
| Thank you and Order status pages (UI extensions, web pixels, post-purchase, public Functions) | Yes | Yes |
| Customer account pages (UI extensions) | Yes | Yes |
| Information, shipping and payment steps (incl. draft order checkouts) | No | Yes |
| Custom apps built with Shopify Functions | No | Yes |
| Checkout Branding API | No | Yes |
| Shopify Checkout Blocks app (free) | Yes, with some features restricted | Yes |
Data checked November 9, 2026 on help.shopify.com.
Every plan also gets the checkout and accounts editor itself, with branding basics such as logo, colors, background and font (Shopify Help Center: customizing checkout). If you are on Basic and an app promises an upsell “in checkout”, check the listing: most of those offers appear on the Thank you or post-purchase page, because the payment step itself is Plus-only.
Why Shopify moved checkout to extensions
Shopify moved checkout to extensions because they are upgrade-safe: Shopify describes them as easy to install and safe to upgrade, while custom code in checkout.liquid had to be maintained by each store. Extensions run in a sandbox and load in fixed places. The move happened in stages, and the last dates have now passed:
- Information, shipping and payment steps:
checkout.liquidis no longer supported (Shopify: apps in checkout). - August 28, 2025:
checkout.liquidand additional scripts sunset on the Thank you and Order status pages for Plus; the additional scripts box became view-only. - April 15, 2026: Shopify Scripts could no longer be edited or published.
- June 30, 2026: all Shopify Scripts stopped running (Shopify changelog).
- August 26, 2026: deadline for non-Plus stores to upgrade the Thank you and Order status pages (upgrade guide). Stores on the Pause and Build plan are upgraded automatically, and that upgrade is permanent.
The practical result: any tracking tag, survey or upsell that lived in old scripts must now come from an app block, a web pixel or a custom pixel.
How to add a checkout extension in 5 steps
There are five steps: install the app, open the checkout editor, add the block, set its checkout behavior, then save and test. You do all five in the Shopify admin, with no code.
Step 1: Install an app that includes a checkout extension
Search the Shopify App Store, click Add app and install it. The listing shows “Checkout” under “Works with” when the app ships a checkout extension.
Step 2: Open the checkout editor
Go to Settings > Checkout. In the Configurations section, click Edit next to the configuration you want to change (on mobile, the button reads Customize).
Step 3: Add the app block
Pick the page from the top menu (for example, Thank you), then click Add block in a section, or open the Apps sidebar and click the plus icon next to the block. Areas the app cannot use are grayed out. A check mark shows a block you already placed.
Step 4: Set the checkout behavior
Click the block to open its settings. Under Checkout behavior you can allow the app to block checkout when information is missing, include the block in Shop Pay (on by default), and expand sections automatically so the block is visible.
Step 5: Save and run a test order
Click Save, then place a test order and look at every page the block touches, on desktop and mobile. For a post-purchase app, also select it under Settings > Checkout > Post-purchase page; that section appears only after the app is configured.
If you are short on time, do Step 5 carefully. Most broken checkout blocks are found only in a real test order.
Using checkout extensions for upsells and bundles
For most stores below Plus, the Thank you page and the post-purchase page are where checkout extensions earn money, because a buyer who has just paid can accept a second offer without re-entering card details. These three apps cover that job; each places its offer through Shopify’s own extension points.
Disclosure: Orichi builds OC: Bundles & Volume Discounts. We compare it with other apps using public Shopify App Store data checked on November 9, 2026.
| App | Rating (reviews) | Price label | Checkout placements |
|---|---|---|---|
| OC: Bundles & Volume Discounts | 5.0 (86) | Free plan; Plus $7.99/month | Thank you page block, post-purchase page |
| Shopify Checkout Blocks | 4.1 (221) | Free | Thank you and Order status content; full checkout on Plus |
| ReConvert Post Purchase Upsell | 4.8 (3,133) | Free plan available | Thank you page, post-purchase; checkout upsells need Plus |
Data checked November 9, 2026 on each Shopify App Store listing.
OC: Bundles & Volume Discounts is a bundle and quantity-break app that also runs Thank you page and post-purchase upsells. Its Thank you page block appears in the checkout editor as “checkout-ui”, offers are created in the app’s “More Upsell” menu, and an accepted post-purchase offer is added to the order the buyer just paid. It supports a second upsell and a downsell when the first offer is declined. Post-purchase and Thank you page upsells are in the Free plan; A/B testing is on the Plus plan only. It is not the right pick if you need custom fields or delivery rules on the payment step.
Shopify Checkout Blocks is Shopify’s own free app and the most direct way to add content blocks, order value limits and, on Plus, custom fields or hidden payment and delivery methods. Its listing shows 155 five-star and 29 one-star reviews out of 221, so read recent reviews before you rely on it.
ReConvert has the largest review base of the three and goes furthest on Thank you page design, with funnels and order status page offers. Its checkout-step upsells need Shopify Plus.
If you want the broader picture, our guide to Shopify upsell at checkout compares offer placements, and the post-purchase upsell guide for Shopify covers the one-click page in detail.
Common checkout extension problems and fixes
Most checkout extension problems come from plan limits, slot limits or leftover old scripts. Check these first:
- The block area is grayed out: the app does not support that area, or the area is Plus-only (information, shipping, payment).
- You cannot add a fourth app: each highlighted area holds at most 3 apps. Remove or move one.
- Your post-purchase app stopped showing: only one app can run the post-purchase page. Check which app is selected under Settings > Checkout > Post-purchase page.
- The block is missing in Shop Pay: open the block and turn on “Include in Shop Pay”.
- Conversions dropped after the upgrade: tags from additional scripts no longer run. Rebuild them as app pixels (from your tracking app) or custom pixels, as the upgrade guide describes.
- A consent app does not appear in Shop Pay: apps that collect privacy consent are not supported in Shop Pay accelerated checkout.
For layout changes beyond app blocks, see how to customize your Shopify checkout page.
FAQ
Do I need Shopify Plus to use checkout extensions?
No. Basic, Grow and Advanced plans can add app blocks to the Thank you, Order status and customer account pages and use a post-purchase page. Plus is needed only for the information, shipping and payment steps, custom Functions apps and the Checkout Branding API.
Are checkout extensions the same as checkout extensibility?
Checkout extensibility is Shopify’s name for the whole system: the checkout editor, branding settings and the extensions apps provide. Checkout extensions are the app parts inside that system.
What replaced Shopify Scripts?
Shopify Functions. Scripts stopped running on June 30, 2026. Discount, shipping and payment rules now come from apps that use Functions, or from a custom Functions app on Plus.
How many apps can I add to one checkout area?
Up to 3 apps per highlighted area. Some apps allow only one instance of their block; once placed, that block is deactivated in the list.
Can a checkout extension slow down my checkout?
Shopify caps each UI extension at 64 KB of compiled code and runs it in a sandbox, so a single block has a limited effect. Test with a real order after adding several blocks. If you see unknown scripts on your checkout, read our note on Shopify checkout hijacking.
Which app should I start with?
Start with the job you need. For content blocks and order limits, Shopify Checkout Blocks is free. For bundles plus Thank you page and post-purchase upsells, compare the options in our best upsell app for Shopify roundup.
Want to try a Thank you page and post-purchase upsell on a Basic plan store? Install OC: Bundles & Volume Discounts from the Shopify App Store and start with the Free plan.
