Quick Summary
Shopify Plus gives you direct access to CRO features like the checkout editor, which allows you to add custom fields, reorder checkout steps, and build post-purchase upsell flows natively.
You also get access to Shopify Functions for custom discount logic and checkout rules, and Checkout Extensibility for adding custom UI blocks to the checkout without editing code directly. These features matter most for stores doing over £1 million a year, where small checkout improvements have a significant revenue impact.
A rough guide: if your store does over £100k a month in revenue, the checkout extensibility and post-purchase upsell features alone can justify the upgrade. Below that level, standard Shopify with well-configured third-party apps is usually sufficient.
Why Shopify Plus Unlocks a Different Level of CRO
On standard Shopify plans, the checkout is largely a closed system. You can change the logo, colours, and basic styling, but you cannot add custom fields, reorder steps, or build custom post-purchase flows without relying on third-party apps.
Shopify Plus removes most of these restrictions. The checkout becomes a configurable surface where you can build the exact flow your store needs, without the performance overhead of stacked third-party apps doing the same job.
The Key Shopify Plus CRO Features
1. Checkout Extensibility
Checkout Extensibility lets you add custom UI components to the Shopify checkout using Checkout UI Extensions. These render natively in the checkout without slowing it down the way third-party app scripts do. You can add custom fields, trust badges, upsell offers, loyalty point displays, and subscription upgrade prompts directly inside the checkout flow.
2. Post-Purchase Upsell Pages
Shopify Plus allows you to build a native post-purchase upsell page that appears between the order confirmation and the thank-you page. This is the optimal position for upsells: the buyer has already committed, their payment details are stored, and accepting the upsell requires a single click with no re-entry of card information.
Post-purchase upsell acceptance rates typically run at 10% to 25%, depending on the relevance of the offer. A store doing 500 orders a month with a 15% acceptance rate and a £35 average upsell adds £2,625 in monthly revenue with no increase in traffic.
3. Shopify Functions
Shopify Functions allows developers to build custom logic that runs server-side within Shopify. For CRO purposes, the most relevant use cases are custom discount functions (building discount structures that go beyond native Shopify discount rules) and checkout validation (running custom rules that determine whether a cart can proceed to purchase).
Examples include: volume-based discounts that apply automatically as cart quantity increases, B2B pricing rules that apply custom rates for specific customer tags, and bundle discounts that apply when specific product combinations are in the cart.
4. Custom Checkout Fields
Plus stores can add custom fields to the checkout via Checkout Extensibility. For stores that need gift messages, personalisation options, delivery date selection, or B2B order references, these fields can be added natively to the checkout without third-party apps. This removes a common source of checkout friction for stores that previously used workaround apps that added extra pages or popups to collect this information.
5. Higher API Rate Limits and Dedicated Support
Shopify Plus stores get higher API rate limits, which matters for stores running real-time inventory sync, complex integrations, or large-scale personalisation. They also get access to a dedicated Shopify Merchant Success Manager and priority support, which reduces the time lost to platform issues that can indirectly hurt conversion rate.
When Shopify Plus Is Worth the Upgrade for CRO
Shopify Plus starts at around £2,000 per month. The upgrade makes sense for CRO purposes when your store is generating enough revenue that the checkout improvements available on Plus produce a return that covers the cost.
If you are evaluating Shopify Plus for CRO improvements, the free audit can help you identify which specific checkout limitations are currently costing you revenue. For stores already on Plus, the CRO engagement includes checkout extensibility implementation as part of the full-funnel work.
Shopify Plus includes Checkout Extensibility for adding custom UI components to the checkout, native post-purchase upsell pages, Shopify Functions for custom discount and checkout logic, and custom checkout fields. These allow you to build checkout flows and upsell systems that are not possible on standard Shopify without relying on multiple third-party apps.
For stores doing over £100k a month, the checkout features on Plus typically pay for themselves. The native post-purchase upsell page alone can add 10% to 25% in revenue on each transaction without additional traffic. Below that revenue level, standard Shopify with well-chosen apps is usually sufficient and more cost-effective.
Checkout Extensibility is Shopify’s API for building custom UI components that render natively inside the Shopify checkout. It allows Plus merchants to add trust badges, custom fields, upsell offers, and loyalty displays without editing checkout.liquid directly. Components built with Checkout Extensibility are forward-compatible with future Shopify updates.
Shopify Plus gives you the ability to create multiple checkout themes and switch between them, which allows for some level of checkout testing. However, true randomised A/B testing in the Shopify checkout still requires a third-party testing tool. Plus removes the restrictions on what you can test, but the testing infrastructure still needs to be built separately.
