> This page is for version v2 (default).
> For other versions, use one of these documentation indexes:
> - v2 (default): https://developers.clearpay.co.uk/v-2/llms.txt
> - v1: https://developers.clearpay.co.uk/v-1/llms.txt

> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://developers.clearpay.co.uk/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://developers.clearpay.co.uk/_mcp/server.

# How to Integrate

Our goal is to make upgrading to Express Checkout as simple as possible for existing Clearpay merchants. There are no new APIs. The only changes you need to make to your existing Clearpay  integration are:

1. Add Express Checkout button to the cart and/or product pages and configure JS with Clearpay  provided key
2. Update the `Create Checkout` and `Auth` (or `Capture Full Payment` if using the Immediate Payment Flow) API call payloads
3. Display the Clearpay Checkout Widget on a review page to enable dynamic updates to the order total after the Express Checkout flow (optional with Integrated Shipping)

![](file:docs/assets/images/924a0f1-AfterpayExpressHappyPath.png "AfterpayExpressHappyPath.png")