Can You Use Square Payments with Shopify? Your Real Options

You already process payments with Square, maybe through your physical store's POS, and you're moving online with Shopify, or already there. Naturally you'd like to keep one payment processor. Then you go to Settings → Payments in Shopify and Square isn't on the list. Here's why, and what your real options are. I recently built a custom Shopify checkout app that integrates Square payments for Genix Flooring, so this comes from hands-on experience.

Why Square isn't a Shopify payment option

Shopify's checkout is closed. Payment providers have to be approved Shopify payments partners and build their integration using Shopify's Payments Apps API. Only then do they appear under Settings → Payments. Square competes directly with Shopify in point-of-sale and e-commerce, so neither side has an incentive to build that integration.

Before going further, check one thing: if Shopify Payments is available in your country, it's usually the simplest option. Many merchants who ask about Square really want one dashboard and low fees, and Shopify Payments plus Shopify POS may cover that. If you have good reasons to stay with Square (existing contracts, a POS setup you won't replace, financing through Square, or reconciliation across several locations), read on.

Option 1: Use Square for in-person sales and Shopify's processor online

The most common setup: Square stays at the counter and Shopify Payments (or another supported provider) handles online checkout. The part that matters is keeping inventory in sync, so you don't sell the same item twice. Several sync apps in the Shopify App Store connect Square inventory and products to Shopify.

Good for: retailers with a physical shop and a regular online store. Downside: two processors, two payout schedules, and reconciliation across both.

Option 2: A custom app that takes payment through Square

When an order really has to be paid through Square, a custom Shopify app can handle that step. The general pattern looks like this (details vary by business):

1. The order is created in Shopify as a draft order, or as an order with payment pending, so products, tax, shipping and customer details all live in Shopify as usual.
2. The customer pays on a page your app controls, using Square's Web Payments SDK to collect the card details securely. Card data goes straight to Square and never touches your server.
3. Your app's backend charges the card with Square's Payments API, using the token the SDK returned.
4. Your app updates the Shopify order through the GraphQL Admin API. It completes the draft order or marks the order as paid, and stores the Square payment ID on the order for reconciliation.
5. Webhooks keep both sides consistent, so refunds or disputes in Square are reflected on the Shopify order.

The exact architecture always depends on the store's order flow, plan and volume. For Genix Flooring, for example, the result was a custom Shopify checkout app that integrates Square payments into the store's checkout flow.

What a project like this involves

• A custom Shopify app with Admin API access to orders and draft orders.
• A Square developer application with sandbox and production credentials.
• A small hosted backend for the payment page, API calls and webhooks.
• Careful testing in Square's sandbox: successful payments, declines, 3-D Secure / SCA challenges, duplicate submissions, refunds and webhook retries.

The trade-offs, honestly

• It isn't Shopify's native checkout. The payment step happens on your app's page. You can design it to match the store closely, but some Shopify checkout features (Shop Pay, some checkout apps, abandoned checkout emails) won't apply to that step.
• Shopify's rules still apply. Shopify may charge third-party transaction fees when you don't use Shopify Payments, and its terms cover how alternative payment flows can be used. Read the current terms for your plan, and talk to Shopify support if you're unsure, before committing.
• You own the maintenance. Both Shopify's and Square's APIs version over time. Plan for periodic updates.
• It fits some business models better than others. Custom orders, quotes, deposits and invoiced B2B sales are natural fits. A high-volume impulse-buy store is usually better served by Shopify's native checkout.

Option 3: Square invoices for special orders

If only some orders need Square (large custom orders or trade customers, for example), there's a low-tech version: create the order in Shopify as a draft, send the customer a Square invoice for the total, and mark the Shopify order as paid once the invoice is settled. It's manual, but it works from day one and costs nothing to build. Many businesses start here and automate once the volume justifies it.

Which option should you choose?

• Normal online store plus a physical shop: Option 1. Shopify's processor online, Square in person, with inventory sync.
• A few special orders a month: Option 3, Square invoices with draft orders.
• Many orders that must go through Square (deposits, quotes, B2B, an existing Square agreement): Option 2, a custom app.

If you're weighing Option 2, the first step is a short technical review of your store, order flow and Shopify plan to confirm it's the right fit before any code is written.