Shopify has disabled its Hosted Payment SDK and the legacy Sezzle payment gateway integration.

This guide describes how to integrate Sezzle into your Shopify website so that you can provide Sezzle as a payment option for your customers. After integrating Sezzle, your Shopify site will:

  1. Offer Sezzle as a payment option on the checkout page.
  2. Refund Sezzle payments from your Shopify order management system.
  3. Display Sezzle promotional messaging.
  4. Authorize and capture payments.

Integration Steps Overview

  1. Install and configure the Sezzle Payments app
  2. Test your integration
  3. (Optional) Sandbox Testing

Before You Begin

  1. You should have a Sezzle merchant account.
  • Please visit our signup page if you don't have an account.
  1. Make sure you have the following Sezzle details handy.
  1. Familiarize yourself with the transaction flow when buying with Sezzle.

Install the Sezzle Payments app

  1. Click on Add app by navigating to the Sezzle Payments app.
  2. Once the app is installed, you will be prompted to enter your production Sezzle public and private API keys.
    For most merchants, we are able to pre-fill the public and private API keys based on the Shopify store. If we cannot uniquely identify the merchant based on the Shopify store, you will be required to fill in the keys.
  3. Click update settings to verify your Sezzle account.
  4. You will be redirected to the payment settings page, where you will need to activate Sezzle Payments for your store.
  5. Click Activate.
  6. Once that is complete you should see Sezzle available as a payment method for your store.

To validate that you’ve successfully installed the new Payments App:
You should see Sezzle Payments installed in your Settings > Payments.


Be sure to activate Sezzle Payments

Without activating Sezzle Payments, Sezzle will not appear in the checkout and the installation process is not complete. Verify this step has been completed.


Install the Sezzle Widget app

The below instructions apply to the private Sezzle app, available for installation only through November 30, 2022. If you are running on the public Sezzle Widget app, please refer to these instructions.

  1. Log in to your website's Shopify admin.
  2. In your Sezzle Merchant Dashboard Setup Checklist, click Install Sezzle Widget app.
  3. Click Get the App.
  4. Click Install App.

Configure Widgets

  1. Within the Sezzle app, enter your Public API Key and click link sezzle account.
  1. Once your account is linked, click add widgets to add widgets to your shop. This process may take a minute.
  1. After widgets have been added, navigate to a product page to confirm that the Sezzle widget has been added.
  1. If you ever need to remove Sezzle widgets from your shop, click the remove widgets button within the Sezzle app.

Note: If the Sezzle app is unable to automatically add widgets to your shop, one of our team members will automatically be notified and will work to manually add widgets to your shop within 7 business days.

Shopify Live Checkout

  1. In the Sezzle configuration page of your Shopify admin, enter the API Keys from your Sezzle Merchant Dashboard and uncheck the Enable Test Mode checkbox, then save the configuration.
  2. On your website, add an item to your cart, then proceed to Checkout and select Sezzle as the payment method.
  3. Click Place Order.
  1. If you are redirected to the Sezzle checkout page, your integration is complete. Congratulations!
  2. Warning Don't complete the payment. Your checkout is now live, so you will be charged if you complete.


If testing was unsuccessful, review the following:

  • Sezzle Shopify extension is the most updated version.
  • Go to Apps > Sezzle, then click About. If there is an option to upgrade, do so now.
  • Sezzle gateway is activated.
  • Go to Settings > Payment Providers and ensure "Sezzle is active" is listed under the Alternative Payment Methods section.
  • API Keys were entered correctly.
  • It is recommended to use the Copy icon in the Sezzle Merchant Dashboard to avoid typos or extra spaces.
  • If you have multiple accounts with Sezzle, the merchant ID and API Keys are tied to only one URL.
  • Widget script is present on your website and reflects the Merchant ID from your Sezzle Merchant Dashboard.
  • Go to a product page on your website.
  • Right-click then select Inspect.
  • In the Elements tab, search for widget.sezzle.

Manual Theme Integration

If the Shopify app fails to maintain the widget script on the product pages, or to add the script manually for additional pages, complete the following steps:

  1. Go to Sales Channels > Online Store > Themes.
  2. Click Actions, then select Edit Code.
  3. In the Code Explorer, go to the Templates folder and select the product.liquid file.
  4. Copy+paste the script to the very bottom of the file, then click Save.
  5. Repeat the previous step in the cart.liquid file.

Note: If you have additional custom product templates, step 4 will need to be repeated for each file, or the script added to a global file, such as layout/theme.liquid.

The script to be inserted into your webpage is as follows:


<script src="{sezzle_merchant_uuid}"></script>
Update {sezzle_merchant_uuid} in the above script template with your site’s Merchant ID (removing the curly brackets), which can be found in the Sezzle Merchant Dashboard.


<script src=""></script>

For assistance with widget configuration, click Request Addition of Widgets in the widget step of your Sezzle Merchant Dashboard Setup Checklist.

Uninstall the Sezzle Widget app

  1. Go to Apps.
  2. Find Sezzle and click Delete.


  1. I have my Shopify Payment Capture set to Manual. What do I need to do?

Sezzle Payments will honor your Shopify Payment Capture setting. If you are set to Manual, then you will need to manually capture payment on orders paid for by Sezzle. The authorization period can vary by Sezzle merchant, so we highly recommend you check the Sezzle authorization expiration at Settings > ecommerce in the Sezzle merchant dashboard. You can adjust this expiration period according to your needs.

  1. I have multiple stores on Shopify. What do I do?

There are several ways to install the payments app on your store. We recommend you use an incognito browser for this process. Navigate to https://{}/admin/settings/payments/alternative-providers/1057901 where the is to be replaced with the URL of your store. Once you log into the store, the rest of the process is the same. To install the payments app for another store, make sure to close the incognito browser and open a new session on the incognito browser.

  1. The order number in Shopify appeared in the merchant dashboard on Sezzle. I don't see it anymore?

Sezzle no longer has access to the Shopify order number. To track orders from Sezzle on Shopify, click the relevant order and then Click on Information from the gateway. The payment ID should match the ID in the Sezzle Merchant Dashboard under the Reference-ID column.


Shopify order details


Reference ID inside Sezzle Merchant Dashboard

You can also search in Shopify Admin for Orders for the payment id using the format receipt.payment_id: <payment_id>.


Searching for an order in Shopify

  1. I have the Sezzle inventory locking feature enabled today. Will this be enabled with the new app?

Unfortunately, no. Sezzle will no longer have access to view and adjust the inventory of a Shopify store. Without these permissions, we are unable to offer this feature alongside the new payment app.

  1. Will I be able to refund orders placed through the legacy gateway after moving to the new app?

Yes, refunds will work as usual from the Shopify Orders page for orders placed through the legacy gateway.

Shopify Sandbox Testing

With the new Sezzle Payments app, sandbox testing can be enabled in your Shopify admin by navigating to Settings > Payments > Sezzle Payments, click Manage, check Enable test mode and click Save. Also, be sure to click the Manage button in Sezzle Payments, enter your sandbox API keys, check Testing with Sandbox API Keys and click update settings.