Checkout UI Extensions 101: Building Post-Purchase and Thank-You Page Customizations
Introduction If you run an online store, the moments after checkout are prime real estate. Checkout UI Extensions let you add lightweight, high-converting elements to the checkout and thank-you pages — think warranty offers, subscription upsells, or quick surveys — without touching payment systems. This guide explains what they are, when to use them, and how to get started in plain language. What are Checkout UI Extensions? Checkout UI Extensions are small pieces of user interface code that run inside Shopify’s checkout and post-purchase (thank-you) pages. They’re sandboxed, which means they can’t access sensitive payment data and are designed to be fast and predictable. In practice, they let you present offers, capture preferences, or trigger backend workflows right after a customer completes an order. Where they run and why that matters Checkout (during payment flow): tightly controlled, minimal UI additions allowed. Post-purchase / Thank-you page: more flexible and ideal fo...