# How to Set Up Cross-Site Testing

This guide walks through the one-time setup required to enable Cross-Site Testing in PDQ.

January 25, 2026

## Table of contents

- [Before You Start](#before-you-start)
- [Step 1. Open the Cross-Site Test Creator](#step-1-open-the-cross-site-test-creator)
- [Step 2. Copy the Cross-Site A/B Test Script](#step-2-copy-the-cross-site-ab-test-script)
- [Step 3. Go to Shopify Admin](#step-3-go-to-shopify-admin)
- [Step 4. Open the Theme Code](#step-4-open-the-theme-code)
- [Step 5. Open theme.liquid](#step-5-open-themeliquid)
- [Step 6. Paste the Script](#step-6-paste-the-script)
- [Step 7. Save the File](#step-7-save-the-file)
- [Important Notes](#important-notes)

Cross-Site Testing lets you split traffic between full Shopify themes and route each theme to a matching checkout experience, ensuring storefront messaging and checkout behavior stay aligned.

## Before You Start

Cross-Site Testing requires:

- At least two Shopify themes
- PDQ installed and active
- Checkout groups already configured in PDQ

The setup is done once per theme.

## Step 1. Open the Cross-Site Test Creator

In PDQ, create a new Cross-Site Test.

Complete the Details and Traffic Allocation steps first.

Proceed to the Installation tab.

## Step 2. Copy the Cross-Site A/B Test Script

In the Installation tab, locate the Cross-Site A/B test script.

Copy the full script.

## Step 3. Go to Shopify Admin

Navigate to:

Online Store. Themes.

You will repeat the next steps for each theme included in the test.

## Step 4. Open the Theme Code

For the theme you want to test, click Edit code.

## Step 5. Open theme.liquid

In the left sidebar, open:

Layout. theme.liquid.

## Step 6. Paste the Script

Paste the script immediately after the opening tag.

Do not modify the script.

## Step 7. Save the File

Click Save to apply the changes.

Repeat Steps 4–7 for every theme in the test.

## Important Notes

- This is a one-time setup per theme. You do not need to repeat it for future tests.
- Once installation is complete, the test is created as a Draft.
- You can start the test at any time from the Drafts view.

Cross-Site Testing is now active and ready to run.