Introducing Cartylabs Checkout: The Checkout Customization App for Modern Shopify Brands

Today we’re launching the Cartylabs Checkout Customization app on the Shopify App Store.

It does one thing: turns your Shopify checkout into a high-converting revenue engine. Customize every step, deliver targeted upsells, and take full control of the experience — built for fast-growing, modern brands on Checkout Extensibility and Shopify Plus.

If you’ve been waiting for a clean, fast, no-code way to actually use the new Shopify checkout — this is it.

Why we built it#

Shopify’s move from checkout.liquid to Checkout Extensibility unlocked the most valuable real estate in ecommerce: the page where intent is highest and friction is lowest. But “unlocked” doesn’t mean “easy.” Most stores look at extensibility, see a developer-shaped problem, and ship the default checkout for another year.

That’s a mistake. Checkout is the single most underused conversion lever on a Shopify store. A free shipping bar that updates live. A one-tap upsell priced under 30% of cart value. Shipping protection. A free gift threshold. Each of these moves AOV by 5–10% on its own — and they compound.

We built Cartylabs Checkout so any merchant can ship all of this in an afternoon, with no developer, no theme edits, and zero added checkout latency.

What’s in the app#

Cartylabs Checkout is a single app with 10+ checkout blocks you can drag into any step — checkout, post-purchase, thank you, or order status:

• Smart upsells & post-purchase offers — AI-recommended add-ons based on cart contents, with one-tap ”+ ADD” buttons. No re-entry of payment.
• Free shipping progress bar — live “Add $X more for free shipping” messaging that updates as the cart changes.
• Free gift threshold — auto-add a low-COGS gift past a target subtotal to pull average orders up.
• Shipping protection — insurance-style add-on with 30–50% attach rates. Pure margin.
• Trust badges, payment icons & social proof — SSL seals, payment logos, and Trustpilot stars right under the pay button.
• Order notes & custom fields — gift wrap, delivery instructions, B2B PO numbers, anything.
• Hide, rename & reorder fields — clean up the default Shopify form without touching code.
• Custom rules & order limits — minimum order values, region restrictions, B2B gating, age verification.
• Advanced validation & error handling — surface real-time errors before the customer rage-quits.
• Thank you & order status blocks — refer-a-friend, post-purchase upsells, tracking widgets, review prompts.
• Branding & UI control — fonts, colors, spacing, banner messaging, all on-brand.

Every block is built on the official Shopify Checkout UI Extensions — so it works on Shop Pay, Apple Pay, Google Pay, and one-page checkout out of the box.

Built for fast-growing, modern brands#

A few things we cared about while building this:

Zero added checkout latency. Checkout is not a place to ship a slow app. Every block is server-rendered, payload-minimal, and avoids client-side blocking work. We measure this every release.

No code. Not “low code.” Not “just a small snippet.” If you can use the Shopify checkout editor, you can configure every block in Cartylabs Checkout. Most merchants are live in under 2 minutes.

Plus-ready, but not Plus-only. Most checkout customization apps gate the good stuff behind Shopify Plus. We don’t. The free plan covers the core blocks every store should ship on day one. Plus features (custom validation, full branding API, advanced rules) light up automatically when you upgrade.

Targeted, not spammy. Upsells are rule-based: cart contents, customer tags, subtotal thresholds, country, currency. Don’t show shipping protection on a $4 sticker order. Don’t show a “complete your bundle” upsell to a customer who already has the bundle. The defaults already handle this; the rule editor lets you tune it further.

Early benchmarks#

Across closed beta merchants, the typical numbers we’re seeing:

• +12% average checkout conversion lift
• +18% average AOV with smart upsells enabled
• 30–50% attach rate on shipping protection
• 2 minutes from install to live blocks
• 0 ms added to checkout response time

These are averages across DTC apparel, beauty, supplements, and home goods. Your mileage will vary by category and traffic mix — but the direction is consistent: checkout is the cheapest conversion gain available on Shopify in 2026.

How it fits with the rest of Cartylabs#

Cartylabs already covers the front half of the funnel:

• Cart drawer with in-cart upsells, rewards progress, free gift, and one-click checkout
• Pricing that scales with revenue, not feature gates

Checkout is the natural next surface. The same product recommendations engine that powers in-cart upsells now powers post-payment upsells. The same rewards bar that runs in the cart drawer runs in checkout. One app store install, one billing line, one consistent shopper experience from product page to thank you page.

If you only run Cartylabs Checkout, that’s fine — it stands on its own. If you run Cartylabs Cart + Checkout together, the funnel is end-to-end.

How to get started#

1. Install Cartylabs Checkout — free plan, no credit card.
2. Open the Shopify checkout editor and drag in the blocks you want. We recommend starting with: free shipping bar, smart upsells, and shipping protection.
3. Place a test order. Watch the AOV move within the first 100 orders.

If you want a hand setting it up, book a demo — we’ll walk through your store, suggest the 3 blocks most likely to move the needle for your category, and configure them with you.

Welcome to the new Shopify checkout. Let’s stop leaving money on the last mile.

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Cartylabs Checkout is live now on the Shopify App Store. Free plan available. Shopify Plus ready.