Install Nex Validator & Enable the App Embed

Install and enable the app embed

Install from the App Store, then enable the Nex Validator app embed in your theme editor. Checkout blocking works without the embed; locking quantity selectors on your storefront does not.

Before you start

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

Steps

1. Install Nex Validator

Search Nex Validator in the Shopify App Store, or use the button below. Approve the permissions and the app appears in your admin under Apps. There is a free trial, and it works on every Shopify plan.

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 it reads App embed is not active, click Enable in Theme Editor. That opens your theme’s App embeds panel with Nex Validator ready to switch on.

4. Toggle it on and Save the theme.

5. Back in the app, click Refresh status. It should now read 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

This trips people up in both directions. Some assume nothing works until the embed is on; others assume the embed alone locks quantity inputs, when that also needs product metafields. How enforcement works explains the split.

Verify it worked

The dashboard reads App embed is active.
Create a test limit and try to check out with a cart that breaks it — 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.