Shopify Checkout Customization Alternatives: A Complete Guide Without Plus

A Croatian shelving retailer landed on our desk asking a question we hear from almost every serious merchant sooner or later: how far can we push the Shopify checkout without paying for Plus? Their catalogue was heavy in every sense, industrial metal shelving sold on load capacity and millimetres, and their instinct was that they needed a bespoke checkout with custom logic to handle it. What they actually needed was almost the opposite. This guide is about the real shopify checkout customization alternatives available to stores that are not on Plus, written from the builds we have shipped rather than from Shopify’s feature matrix.

We will be blunt about a thing most guides tiptoe around: the checkout is the single place where Shopify gives you the least room, and for most stores that is a feature, not a bug. The interesting work almost always lives just before and just after checkout, not inside it.

TL;DR

• OUR POSITION: For the overwhelming majority of non-Plus stores, the right move is to stop trying to rebuild the checkout and instead move your customization budget to the product page, cart, and post-purchase, where you own the surface and conversions actually move. We proved this with a Croatian shelving retailer who kept the native checkout untouched and still lifted conversions by 18%.
• WHAT YOU CAN AND CANNOT DO: On basic, Shopify, and Advanced plans you get checkout branding, some app blocks via Checkout Extensibility, and post-purchase pages; you do not get scripts, full field control, or arbitrary logic. Know which side of that line your requirement sits on before you scope anything.
• WHEN TO GO CUSTOM: Building a headless or fully custom flow is justified only when the buying logic itself is the product, as with the hotel booking engine we built against PMS APIs. If your checkout requirement is cosmetic or trust-related, custom is the expensive wrong answer.

Step 1: Define what you actually mean by “checkout customization”

The first thing we do when a store like Metalne Police comes in asking for checkout changes is force a distinction that clients rarely make on their own. “Checkout” gets used to mean three different things, and each has a completely different set of alternatives.

There is the pre-checkout experience: product page, collection filtering, cart drawer, and the moment someone commits to buy. There is the checkout itself: the shipping and payment steps Shopify hosts. And there is post-purchase: the thank-you page, order status, and follow-up. When a client says “we need to customize checkout,” roughly eight times out of ten the requirement they describe lives in the first or third bucket, not the middle one.

With the shelving retailer, the CEO’s original brief mentioned a “custom checkout” because their old-school buyers were used to phone orders and spec sheets. When we unpicked it, the real requirement was: make a first-time visitor confident that these shelves fit their garage and hold their load before they ever reach payment. That is not a checkout problem. That is a product-data-as-interface problem, and it is solvable on a standard plan.

Why does this distinction save money?

Because the three buckets have wildly different price tags. Pre-checkout and post-purchase work sits in your theme and in apps you fully control. Checkout-step work, on non-Plus, is constrained to what Shopify’s Checkout Extensibility exposes, and everything beyond that requires Plus or a headless rebuild that can cost more than a year of Plus. Sorting the requirement into the right bucket on day one is the single highest-leverage decision in the whole project.

Pro Tip: When a client insists the requirement is “in checkout,” we ask them to record their screen doing a real order and narrate what is missing. On the shelving project this exercise revealed the gap was on the product page, load-capacity confusion, not at payment at all. Ten minutes of screen recording saved us from scoping a checkout rebuild nobody needed.

Checkpoint: You have confirmed this step when every checkout requirement on your list is tagged pre-checkout, checkout-step, or post-purchase, and you can point to the exact screen where each one lives.

Step 2: Map your requirement against what non-Plus actually allows

Once the requirements are sorted, we map them against the hard boundaries of what Shopify permits without Plus. This is where a lot of teams waste weeks, they scope something the platform will simply refuse to let them ship.

Shopify’s Checkout Extensibility opened up a defined set of app-based customizations that are available on all plans, replacing the old checkout.liquid approach that only Plus stores could touch. That is genuinely more than was possible a few years ago, but it is a fenced garden. You can add UI extensions in specific slots, apply branding through the checkout branding API, and use post-purchase extensions. You cannot rewrite the field order, inject arbitrary scripts, or bolt on custom validation logic outside the sanctioned extension points unless you are on Plus.

Here is how we lay it out for clients so nobody argues about it later.

Requirement	Basic / Shopify / Advanced	Shopify Plus	Where we usually solve it instead
Logo, colours, fonts at checkout	Yes, branding API	Yes	Checkout branding settings
Add trust badges / delivery note	Yes, UI extension app block	Yes	Checkout UI extension
Reorder or hide checkout fields	No	Yes, checkout editor	Rarely needed; rethink the ask
Custom line-item discount logic	No (Scripts is Plus)	Yes, Functions	Cart-level app or product bundling
Fully custom multi-step flow	No	Partially	Headless build, only if justified
Post-purchase upsell	Yes, app	Yes	Post-purchase UI extension
Localised currency and language	Yes, Markets	Yes	Shopify Markets

The last row mattered enormously for the shelving client. They needed a single native checkout localised in EUR for the Croatian market, and Shopify Markets handles that on a standard plan with zero custom code. We did not touch the checkout logic once. We configured Markets, and the “checkout customization” line on their brief closed itself.

Contrast that with a requirement that genuinely cannot live inside Shopify’s checkout at all. When we built our custom hotel booking engine, the entire buying logic, availability, rate rules, multi-night pricing, PMS synchronisation via SiteMinder, was the product. No amount of Checkout Extensibility gets you there, because the “checkout” in hospitality is an availability engine, not a cart. That is the clearest signal we know that you have left Shopify checkout territory entirely and need a different architecture.

Checkpoint: You have finished this step when every requirement in your list has a Yes or No against non-Plus in the table above, and every No has either a pre/post-purchase alternative or an explicit decision to go headless.

Step 3: Redesign the pre-checkout surface (this is where conversions actually move)

Here is the Presta opinion that pushes hardest against the standard advice. Most guides on this topic funnel you toward checkout apps and Plus upgrades. After doing this for clients, we think that is backwards. The checkout is the least leveraged surface you have, because Shopify has spent a decade optimising the default flow across millions of stores. You are very unlikely to out-convert Shopify’s own checkout by tinkering with it. The leverage is in getting the right, confident buyer into that checkout in the first place.

Heavy products do not need a heavy platform. What they need is the answer to the buyer’s question before they reach the cart.

On the shelving project this was the whole game. We treated specifications as the interface. Instead of downloadable PDF spec sheets and a phone number, we put structured product data directly into the UI: browse by space (garage, warehouse, retail backroom), filter by size and load capacity per shelf, and answer the fit-and-capacity question on the product page itself. A first-time visitor can now go from “I need shelves for my garage” to a completed order without contacting anyone. That reorganisation, entirely upstream of checkout, is what drove the 18% conversion lift, not a single line of checkout code.

What does “specifications as the interface” mean in practice?

It means the buyer’s decision criteria become your navigation and your filters, not an afterthought buried in a description. For an industrial retailer, dimensions and load capacity are the decision. So they became the primary filters and the most prominent product-page data, presented as structured metafields rather than free text. We migrated their spec data into Shopify metafields and rendered it in the theme, which is standard-plan work with no checkout involvement whatsoever.

The same principle scales up brutally. Our Shopware build for a German consumer-goods distributor, H. Ludendorff GmbH, carries roughly 1.2M articles from 400+ manufacturers across sanitation, heating, solar and tools. At that scale the storefront is really a data-interchange project wearing an ecommerce hat, they even publish product data in DATANORM so tradespeople can import it into estimating software. Nobody at Ludendorff was asking to customize the checkout. The entire engineering problem was getting a catalogue that large to be findable and filterable, which is pre-checkout work by definition. That build came with ERP integration and increased their revenue by 80%. Not one percent of that came from checkout customization.

If you want to understand why we lean so hard toward Shopify for this kind of catalogue-heavy retail, we wrote up the architectural reasoning behind treating Shopify as more than a platform separately.

THE CONFIDENT-BUYER FRAMEWORK is how we run this stage with every catalogue client:

1. Identify the buyer’s decision question. For shelving it was “will it fit and hold my load?” For cosmetics it was skin type and concern. Name it in one sentence.
2. Turn that question into structured data. Metafields, not prose. Filterable, not buried.
3. Make the answer visible before the cart. On the collection page and the product page, not in a downloadable file.
4. Remove the human touchpoint that used to answer it. Kill the “call us” fallback once the interface answers the question.
5. Measure whether contacts drop and self-serve orders rise. If buyers still call, the interface has not answered the question yet.

Checkpoint: This step is done when a first-time visitor who has never spoken to your team can find, understand, and commit to the right product without any human contact, and you have watched a real user do it.

Step 4: Use Checkout Extensibility for the things it is genuinely good at

We have spent three steps steering you away from the checkout. Now we will steer you back, but only for what Checkout Extensibility does well. On non-Plus plans, the sanctioned customizations are worth using, they are just narrower than most people hope.

The two we deploy most often are branding and trust reinforcement. Getting the checkout to visually match the store, correct logo, brand colours, fonts, via the branding API removes a jarring transition that quietly erodes trust. And a UI extension that restates a delivery promise or a returns guarantee at the payment step can reassure a nervous buyer at exactly the right moment. These are small, cheap, and worth doing. We typically budget half a day to a day of configuration for branding plus one focused extension, based on past projects; that is a Presta estimate from scoping, not a measured client figure.

When is a post-purchase extension worth building?

When you have a genuine complementary product and a repeat-purchase pattern. Post-purchase upsell extensions on non-Plus can add a one-click offer after payment without disrupting the main flow, which is one of the few places you can add real revenue inside Shopify’s checkout territory. We are cautious here. A bad post-purchase offer trains customers to distrust your thank-you page. We only recommend it when the offer is obviously useful, a matching accessory, a consumable refill, not a random discount grab.

Pro Tip: On a cosmetics engagement we delivered through 2024, the post-purchase surface was the right place for refill and complementary-product prompts because the buying pattern is genuinely repeat-heavy. That store, built as a Shopify state-of-the-art store with ERP integration, increased revenue by 80%. The post-purchase work was a slice of that, but the point is it fit the buying behaviour. We would not have shipped the same upsell for the shelving client, because you buy a shelving system once and then you are done for years. Match the checkout-adjacent tactic to the purchase frequency, not to what is technically possible.

Checkpoint: You know this step worked when your checkout branding is visually indistinguishable from your store and any extension you added either raises AOV or reduces payment-step abandonment, measured, not assumed.

Step 5: Handle the requirements that need scripts or field logic without paying for Plus

This is the step where clients get stuck, because it is the genuine hard boundary. Custom discount logic, conditional field behaviour, and line-item manipulation historically lived in Shopify Scripts, which is Plus-only, and now live in Shopify Functions, which have their own plan gating for the more powerful checkout-facing capabilities. If your requirement genuinely needs this, you have three honest options.

Option one: solve it before checkout. A surprising amount of “checkout logic” can be moved into the cart or product configuration. Bundle products so the discount is baked into a single line item. Use a cart-level app to apply promotions before the customer hits the hosted checkout. This is our default recommendation because it keeps you on your current plan and inside surfaces you control.

Option two: reframe the requirement as a merchandising problem. On the shelving project, one early ask was “can we give trade customers automatic tiered pricing at checkout?” On non-Plus that is awkward. We reframed it: separate the trade buyers into a segment with their own pricing, rather than trying to compute tiers in a checkout they could not modify. For their volume and buyer base, that was cleaner than the automation they had imagined, and it needed no checkout logic at all.

Option three: accept that you need Plus, or headless. Sometimes the requirement is real and unavoidable. If you are running complex B2B pricing rules, per-customer catalogues, or checkout validation that must run server-side at the payment step, Plus exists for a reason and it is cheaper than a bespoke rebuild. We say this plainly because “avoid Plus at all costs” is a false economy when the requirement is genuinely a checkout-logic requirement.

Here is how we decide, with rough effort estimates from our scoping.

Requirement type	Our default solution	Effort (Presta estimate)	Plan needed
Discount that could be a bundle	Product bundling in cart	2-4 days	Any plan
Promo applied before checkout	Cart-level app or draft orders	1-3 days	Any plan
Tiered / trade pricing	Customer segments + pricing rules	3-6 days	Any plan (B2B on Plus for full features)
True checkout-step validation	Shopify Functions	1-2 weeks	Plan-gated, often Plus
Fully bespoke buying logic	Headless / custom engine	6-12+ weeks	Custom

Those day ranges are our estimates from past scoping, not guaranteed timelines, and not tied to any single client. We share them so you can sanity-check quotes.

Checkpoint: This step is complete when every checkout-logic requirement has been either moved upstream, reframed as merchandising, or explicitly costed as a Plus or headless decision with a number attached.

Get a straight answer on whether you actually need to touch checkout

If you are staring at a checkout requirement and cannot tell whether it needs Plus, a clever app, or nothing at all, that ambiguity is exactly what our ecommerce team untangles on a scoping call. We build and migrate on Shopify, WooCommerce and Shopware, and most of the time we talk clients out of the expensive checkout rebuild they thought they needed and into the pre-checkout work that actually moves conversions. This is for merchants with real catalogues and real buyers; it is not for someone who just wants a different button colour, you can do that yourself. If you want a candid read on which side of the line your requirement sits, talk to our ecommerce team.

Step 6: Build the custom path only when the buying logic is the product

We keep the fully custom route in its own step because it is the exception, not the fallback, and treating it as a fallback is how projects blow their budget. There is exactly one situation where we recommend leaving Shopify’s checkout entirely: when the buying logic itself is your product and cannot be expressed as a cart.

The clearest example in our portfolio is the custom hotel booking engine we built. Hotels are almost universally stuck with rigid, iframe-embedded third-party booking tools that they cannot brand, cannot instrument, and cannot control. We built a fully custom, fully branded engine that integrates with SiteMinder and other PMS systems via API. Decoupling the frontend from the booking logic gave complete UX control plus GA4/GTM conversion tracking that traditional systems simply cannot expose. That engine now lets a client run multiple locations from one custom-made booking engine, saving cost and time.

Notice why that justified going custom: availability, rate calendars, and multi-night logic are not a shopping cart. You cannot bolt them onto Shopify checkout at any plan tier. The buying logic was genuinely the product. Our approach there is the same principle we would apply to any custom checkout: separate the frontend from the business logic, integrate at the API level, keep the interface fully branded and conversion-optimised with a step-by-step flow, instant feedback and clear error states, and instrument every step with analytics.

How do you know your requirement is really a “custom” requirement?

Ask whether a standard product, variant, and cart can represent what you sell. Metal shelving can: a product with dimension and load metafields, variants for size, a quantity in a cart. So Shopify’s checkout was correct and we never considered custom. A hotel night with dynamic availability across a PMS cannot be represented as a static product, so custom was correct. If your answer is “sort of, with a lot of hacks,” you are on the boundary and should cost both routes before deciding.

Pro Tip: The trap we have watched teams fall into is building custom to avoid a monthly plan fee. We ran the maths on this for more than one prospect: a headless or custom checkout that we would estimate at 6 to 12 weeks of build plus ongoing maintenance almost never pays back against a Plus subscription unless the buying logic is genuinely un-cartable. Do not build a booking engine to save a subscription; build one because you are actually selling availability.

Checkpoint: You should only proceed down the custom path when you can articulate, in one sentence, why your buying logic cannot be represented as a Shopify product, variant and cart, and when you have costed the build against the Plus alternative.

Common Mistakes

We see the same three errors on nearly every store that arrives believing it needs checkout customization.

Mistake: Trying to fix a trust or clarity problem inside the checkout. Why It Happens: The customer abandons at the payment step, so teams assume the checkout is the problem, when the doubt was seeded three pages earlier. Fix: Move the reassurance upstream to the product page and cart, where you have full control, and use the checkout only to restate the promise you already made.

Mistake: Scoping checkout logic the plan will never allow. Why It Happens: Teams read about Scripts or Functions without checking the plan gating, then design a flow that requires capabilities their tier does not have. Fix: Map every logic requirement against your actual plan before design, using the table in Step 5, and reframe or move anything that lands in the No column.

Mistake: Going headless to save a subscription fee. Why It Happens: A custom build looks cheaper than years of Plus on a spreadsheet, ignoring maintenance, security, and the opportunity cost of engineering time. Fix: Only go custom when the buying logic cannot be a cart; otherwise pay for Plus, which is what we told the shelving client would have been the right call had their requirement been real, which it was not.

Measuring success: 30, 60 and 90 day outcomes

We do not sign off checkout-adjacent work on vibes. Here is the measurement rhythm we run, built from what we tracked on the engagements in this article.

At 30 days we look for leading indicators, not revenue. For the shelving retailer the key early signal was a drop in inbound “will it fit / will it hold” contacts, because that told us the specifications-as-interface work was answering the question the checkout could never answer. We also watch product-page-to-cart rate, because if the pre-checkout work is right, more people commit before they ever reach payment.

At 60 days we look at checkout completion and cart abandonment. This is where branding and trust extensions should show up if they are working. If completion has not moved, the extension was cosmetic and we say so.

At 90 days we look at conversion rate and, where it is a fair comparison, revenue against the prior setup. The shelving client’s 18% conversion increase against their previous setup is the kind of figure we hold ourselves to at this mark. For the booking engine, the equivalent 90-day proof was operational: one engine running multiple locations, which is a cost-and-time saving rather than a conversion metric, and we measure it that way rather than pretending it is a conversion story.

Window	What we measure	What good looks like
30 days	Inbound spec contacts, product-to-cart rate	Contacts drop, add-to-cart rises
60 days	Checkout completion, abandonment	Completion up, abandonment down
90 days	Conversion rate, revenue vs prior setup	Sustained conversion lift

Checklist we run before calling any checkout-adjacent project a success:

• Baseline: Captured the prior conversion and abandonment rates before we changed anything.
• Attribution: Confirmed GA4/GTM tracks each pre-checkout and checkout step distinctly.
• Contact volume: Measured whether human touchpoints for buying questions actually fell.
• Completion: Verified checkout completion moved, not just top-of-funnel traffic.
• Comparison: Compared against the real prior setup, not an idealised baseline.

Advanced tips for pushing non-Plus checkout further

A few things we have learned that do not fit neatly into the numbered steps.

Use Shopify Markets aggressively before you consider anything custom for localisation. The shelving client’s entire “localised checkout” requirement collapsed into a Markets configuration. For any European seller, currency and language localisation is a solved problem on standard plans, and we see teams overbuild here constantly.

Instrument before you optimise. The reason we can say the booking engine’s decoupled frontend gave conversion tracking that traditional systems cannot expose is that we treat analytics as a build requirement, not an afterthought. On Shopify, get your GA4 and GTM checkout events verified early, because you cannot improve a step you cannot see.

Treat metafields as your real product model. The difference between the shelving store and the Ludendorff catalogue is scale, not concept: both are structured-data problems solved by putting the buyer’s decision criteria into fields that drive filtering and display. Almost every “we need a custom checkout” ask we receive from a catalogue business is actually a “our product data is unstructured” problem in disguise.

If you are weighing this alongside a platform decision, our Shopify agency services guide and our writeup on how to evaluate a Shopify migration agency cover the surrounding decisions. And if you are coming from WooCommerce specifically, the benefits of moving WooCommerce to Shopify piece is the honest version of that trade-off.

To close the loop on the shelving retailer: they arrived convinced they needed a custom checkout for old-school buyers, and we shipped a brand-new Shopify store with an entirely native, EUR-localised checkout that we did not customize at all. All the work went into treating specifications as the interface. The result was an 18% conversion lift and buyers who no longer need to phone anyone. As their CEO put it, “Our clients are usually old school and they need a very straightforward and easy way of online shopping. Presta delivered exactly that.” What we would do differently now is push the screen-recording exercise from Step 1 even earlier, because it is the fastest way to prove the checkout was never the problem.

If you are just getting started, prioritise Step 1 and Step 3: sort your requirements into buckets and fix the pre-checkout surface first, because that is where conversions move and where you have full control. If you are auditing something that already exists, start with Step 2 and the measurement section: map what you have built against what your plan allows, and check whether anything you paid for at the checkout step is actually moving a number.

Next Steps:

• Record a real order on your store and tag every gap as pre-checkout, checkout-step, or post-purchase.
• Move your two highest-value buyer decision criteria into structured metafields and expose them as filters.
• Baseline your current conversion and abandonment rates today, before you change anything.

Frequently Asked Questions

What are the real alternatives to Shopify Plus for checkout customization?

The honest answer is that most of the alternatives are not checkout customizations at all, they are pre-checkout and post-purchase changes that solve the underlying problem. On non-Plus plans you get Checkout Extensibility for branding, sanctioned UI extensions, and post-purchase extensions, plus Shopify Markets for localisation. Those cover the large majority of genuine requirements.

For anything beyond that, your alternatives are to move the logic upstream into the cart or product configuration, to reframe it as a merchandising problem such as customer segments, or, if the buying logic genuinely cannot be a cart, to go headless. We recommend them in that order because that is the order of increasing cost and decreasing reversibility.

How can I customize my Shopify checkout without Plus?

Start with the checkout branding API to match your store’s logo, colours and fonts, which removes the jarring visual break that quietly loses trust. Then add a checkout UI extension only if you have a specific reassurance to deliver at the payment step, a delivery promise or returns guarantee, rather than adding extensions because you can.

Beyond that, the most effective “checkout customization” is done before checkout. On our shelving build we changed nothing inside the hosted checkout and still lifted conversions by 18%, purely by fixing the product page and filtering so buyers arrived confident. If your goal is more completed orders, that is where the effort belongs.

What checkout customization options are available on basic Shopify?

Branding through the checkout branding settings, checkout UI extensions via apps, post-purchase upsell extensions, and full localisation through Shopify Markets are all available on basic, Shopify and Advanced plans. What you do not get is Shopify Scripts, arbitrary field reordering or hiding, and the full range of checkout-facing Functions capabilities, which remain plan-gated toward Plus.

In practice the basic plan is more capable than most people assume, because Checkout Extensibility replaced the old Plus-only checkout.liquid model with app-based customizations available to everyone. The limits you will hit are around custom logic at the payment step, not around appearance or reassurance.

Should I move checkout logic into the cart instead?

Almost always, yes, if the logic can be represented there. Discounts that could be a bundle, promotions applied before the hosted checkout, and pricing that can be handled through customer segments all belong in the cart or product configuration, where you keep full control and stay on your current plan. We reach for this before anything else.

The exception is validation or logic that must genuinely run server-side at the payment step, which cart-level solutions cannot fake. If you have tried to move it upstream and it still leaks into the checkout, that is your signal that the requirement is real and you are looking at Functions on a gated plan or Plus.

When does it make sense to bring in Presta for this?

Not every store needs an agency for checkout work. If your requirement is branding, one reassurance extension, and Markets localisation, you can do that yourself with a weekend and Shopify’s docs, and you should. We would rather tell you that than sell you a project you do not need.

It becomes worth bringing us in when you have a real catalogue with structured-data problems, when you cannot tell whether a requirement needs Plus or a clever app or nothing, or when you are seriously weighing a headless or custom build and want the maths run honestly before you commit six weeks of engineering. That is the threshold: ambiguity plus scale, or a buying-logic requirement that might not be a cart at all. On the shelving project our value was talking the client out of the custom checkout they thought they needed. If you want that same candid read, our ecommerce team does exactly this.

Is going headless worth it just to control the checkout?

Only when the buying logic itself is the product. We built a fully custom hotel booking engine precisely because hotel availability, rate rules and PMS synchronisation cannot be expressed as a Shopify cart, and that decoupling gave the client complete UX control, conversion tracking, and the ability to run multiple locations from one engine.

For a standard product-and-cart business, going headless to control the checkout is usually a false economy. Our rough estimate from past projects is that a custom checkout build lands at six to twelve weeks plus ongoing maintenance, which rarely pays back against a Plus subscription unless your logic is genuinely un-cartable. Build custom because you sell something a cart cannot represent, not to dodge a monthly fee.

Will Shopify’s upcoming releases change what non-Plus stores can do at checkout?

Shopify’s platform capabilities shift with each release, and Checkout Extensibility in particular has been expanding what is possible without Plus over successive updates. It is worth tracking what changes each cycle, because a requirement that needs Plus today may become available on standard plans later. We keep an eye on this so clients do not overbuild against limits that are about to move.

If you want to plan around the roadmap, our writeup on what to expect from Shopify Winter 2026 is where we track the release-specific detail. The general principle holds regardless of the release: solve upstream first, and only reach for checkout-step capabilities when nothing before checkout will do.

How do I know if my “checkout problem” is really a product data problem?

Ask whether your buyers can answer their key decision question before they reach the cart. For the shelving retailer the question was “will it fit and hold my load,” and until we put dimensions and load capacity into structured, filterable data on the product page, buyers had to phone in, which looked like a checkout friction problem but was really a data-presentation problem.

The tell is unstructured product information: specs living in PDFs, free-text descriptions, or a “call us” fallback. The same pattern held at massive scale on our Ludendorff Shopware build with its 1.2M articles, where the entire engineering challenge was structured data and interchange, not checkout. If your product data is unstructured, fix that first and watch how many “checkout” complaints disappear.

Sources

• Shopify Checkout UI Extensions documentation
• Shopify Customer Account and Checkout Branding API
• Shopify Functions documentation