Install Nex Validator & Enable the App Embed

Install and enable the app embed

Install Nex Validator from the Shopify App Store, then enable the app embed in your theme editor. Checkout blocking can work without the app embed, but storefront features such as quantity locking need it enabled.

Before you start

A published Online Store 2.0 theme.
Permission to edit your theme.

Steps

1. Install Nex Validator

Search for Nex Validator in the Shopify App Store, or use the button below. Install the app and approve the required permissions. Nex Validator will then appear under Apps in your Shopify admin. A free trial is available, and the app works on all Shopify plans.

Install on Shopify Already installed? Skip ahead

2. Open the app. The dashboard shows a Your setup card with the app embed status.

3. If the status says App embed is not active, click Enable in Theme Editor. Shopify will open the App embeds section of your theme, where you can turn on Nex Validator.

4. Turn on the Nex Validator app embed, then click Save.

5. Return to Nex Validator and click Refresh status. The setup card should now show App embed is active.

What the embed does and does not control

	Needs the app embed?
Blocking checkout when a cart breaks a rule	No — works immediately
Locking the quantity selector on product pages	Yes
Showing the message on the cart page	Yes

The app embed is not required for checkout blocking, but it is required for supported storefront features. Quantity locking may also need product setup, so enabling the app embed alone may not lock the quantity selector. See How enforcement works for more details.

Verify it worked

Check that the dashboard shows App embed is active.
Create a test limit and try an order that does not meet the rule. Checkout should be blocked.

Create your first limit.

Frequently asked

Do my rules work without the app embed?

Checkout blocking does. Storefront quantity locking does not — that layer is delivered by the theme extension, which the embed switches on.

Where do I find the app embed?

Online Store → Themes → Customize → App embeds. The dashboard also has an "Enable in Theme Editor" button that opens it directly.

I enabled it but the dashboard still says inactive.

Save the theme, then use "Refresh status" on the dashboard. The check reads your published theme, so an unsaved editor session will not register.

Does the embed slow my storefront down?

It adds a small script that reads product metafields and sets the quantity input bounds. Checkout validation itself runs inside Shopify and adds nothing to your theme.