In short
Since checkout.liquid ended, Shopify checkout is customized with four tools. The checkout editor handles your logo, colors and fonts from the Basic plan up. Apps and their UI extensions add blocks, messages or upsells. Shopify Functions change discounts, shipping and payment, and pixels take care of tracking.
The line with Shopify Plus runs through the information, shipping and payment steps. Outside Plus, blocks only go on the Thank you and Order status pages, and a Function always comes through a public App Store app. If a customization vanished, check these dates: August 13, 2024 for checkout.liquid inside checkout, August 28, 2025 for the Thank you and Order status pages on Plus, June 30, 2026 for Shopify Scripts, August 26, 2026 for the Thank you and Order status pages on every other plan.
You want to ask for a membership number at checkout, show a message about your shipping times, offer a product after payment, or hide cash on delivery above a certain order value. Or your conversion tracking went silent on the Thank you page, and nobody touched a thing.
The answer depends on which part of checkout you're aiming at, and on your plan.
What can you change in Shopify checkout, and on which plan?
Shopify sorts its settings into two tiers. Standard customizations are open from the Basic plan up, advanced features stay reserved for Plus (help.shopify.com).
| What you want to do | Which tool | Outside Plus | On Plus |
|---|---|---|---|
| Logo, colors, fonts, one-page or three-page checkout | checkout and accounts editor | yes | yes |
| Branding beyond the editor | Checkout Branding API | no | yes |
| Delivery instructions, gift message | editor custom fields | yes | yes |
| Any other field (text, list, date, checkbox) | editor custom fields | no | yes |
| Block, message or upsell on the Thank you and Order status pages | app with a UI extension | yes | yes |
| Block, message or upsell in the information, shipping, payment steps | app with a UI extension | no | yes |
| Discount, shipping or payment following your rules, blocked cart | Shopify Functions in a public app | yes | yes |
| The same logic coded for your store only | Shopify Functions in a custom app | no | yes |
| Conversion tracking | app pixel or custom pixel | yes | yes |
For the editor and apps, "outside Plus" means the Basic plan or higher.
Why did your checkout customization disappear?
checkout.liquid was the theme file Plus stores used to edit checkout code. Shopify announced its end in February 2023, and it has stopped working on the information, shipping and payment steps since August 13, 2024 (changelog.shopify.com).
The Thank you and Order status pages followed. According to the developer docs, Shopify retired checkout.liquid and additional scripts there on August 28, 2025, along with app script tags for Plus stores on the same date. On other plans, script tags on those pages end on August 26, 2026 (shopify.dev).
Since August 28, 2025, the additional scripts section in your checkout settings is view-only. August 26, 2026 was the deadline for non-Plus stores to move to the new Thank you and Order status pages (help.shopify.com).
Shopify states that automatic upgrades began in January 2026, and that customizations made with additional scripts, apps using script tags or checkout.liquid on those two pages are lost (help.shopify.com). If your Google tag or your thank-you message is gone, that's the first thing to check.
To see where you stand, open the checkout settings in your admin and look at the Configurations section. An upgrade notice means your store still runs on the old pages, and the guide Shopify generates lists your customizations one by one.
Plus stores also lost Shopify Scripts in Ruby, retired on June 30, 2026 (help.shopify.com). I cover their replacement in my article on migrating Scripts to Functions.
What can you change without code in the checkout editor?
The checkout and accounts editor is open from the Basic plan up. You add your logo, change the color of buttons and links, pick a font from a list, and switch between a one-page and a three-page checkout (help.shopify.com).
Since February 5, 2026, the editor won't take a new background image in the header or the main content area (help.shopify.com). Only the order summary still accepts one.
For a field, check your plan before you go shopping for an app. Custom fields are added as blocks in the editor, with no app, and each answer is saved to an order metafield. Every field type is reserved for Plus, other plans only get Delivery instructions and Gift message (help.shopify.com).
A field applies to the whole order. You can't add one for a single product in the cart or for one shipment. Shopify also warns that making a field required can lower checkout conversion.
Shopify publishes its own free app, Checkout Blocks. It adds content blocks to the Thank you and Order status pages without code, and Plus stores can extend it to the full checkout.
Adding a block, a message or an upsell: what's reserved for Plus?
A block at checkout is a checkout UI extension, shipped by an app. Extensions for the information, shipping and payment steps are only available to Plus stores (shopify.dev).
Outside Plus, apps that add blocks to the Thank you and Order status pages work from the Basic plan up (help.shopify.com). That's where a post-purchase upsell or a note about your shipping times goes.
Shopify has two kinds of placements. A block goes wherever you put it in the editor. A static target renders on its own in a fixed spot, and you can't move it.
Outside Plus, no app can place a block in those three steps. If that block is your only reason to move to Plus, weigh the plan's price against what the block needs to earn you before you sign.
Discounts, shipping, payment: what do Shopify Functions allow on your plan?
Functions change checkout logic, meaning what Shopify calculates and offers your customer. They cover discounts, delivery options, payment methods, cart validation, bundles and pickup points (shopify.dev).
The plan rule fits in two sentences. Every store can use a public App Store app that contains Functions. Only Plus stores can use a custom app that contains them (shopify.dev).
Outside Plus, a rule specific to your store goes through a public app. On Plus, I can code a Function for your store only and ship it in a custom app.
Some operations stay reserved for Plus, whatever the app. A payment Function can rename, reorder or hide the methods on offer, but payment terms and review for B2B orders require Plus (shopify.dev). To change the price of a cart line, the update operation is limited to Plus stores and development stores (shopify.dev).
On the shipping side, a Function renames, sorts or hides the delivery options on offer. Shopify doesn't let you preselect a pricier option, the cheapest one has to stay first (shopify.dev).
Validation stops the customer from moving through checkout when a condition isn't met, with an error message on the relevant field (shopify.dev). A minimum quantity or a forbidden product mix gets handled this way.
How do you track conversions without additional scripts?
Tracking runs through pixels, managed in your admin. App pixels come with a marketing or data collection app, and a developer adds custom pixels in the pixels manager (help.shopify.com).
Shopify runs them in a secure sandbox. The Thank you page supports app pixels for tracking and analytics (help.shopify.com).
An old snippet pasted into additional scripts gets rebuilt as a pixel. I then place a real test order to check that every event reaches your tracking tool.
What does a developer actually set up on your checkout?
I start with the inventory. The customizations report in your admin and the upgrade guide list what ran on your old pages, scripts and apps included.
For each need, I look for the native setting first, then a solid app, and I only write code when nothing fits. Each app adds one more dependency on the step where the sale happens, and I've written about measuring what your apps really cost you.
When code is needed, I write the UI extension or the Function inside an app, deploy it with Shopify CLI, and test it on a draft checkout configuration before publishing.
Then I run every case by hand with a real cart, a discount code, an address abroad and each payment method you offer.
Where should you start with your checkout?
Write down what you want to change and at which checkout step, then compare it with the table at the top. If your need lands on a "no" outside Plus, or if you don't know what ran on your old pages, book a 30-minute call with me.
I look at your plan and your current customizations, then tell you what works natively, through an app or with code. The price is set during that call, and you can see the kind of projects I deliver in my portfolio section.
