Required product rules
Make an item mandatory whenever another product is in the cart — refills, accessories, warranties and bundle completeness.
IF cart contains Espresso Machine
AND cart does not contain Water Filter
THEN block checkout
Prevent invalid carts.Protect every order.
Create powerful cart rules for required products, compatibility and quantities. CartGuard compiles them into Shopify's own checkout validation, so invalid carts are stopped before they become orders.
What CartGuard does
Rules that hold at checkout
Every rule below is enforced by a Shopify Function running inside Shopify, including express checkouts.
Compatibility rules
Stop combinations that cannot be sold together, by product, variant, collection, tag, vendor or product type.
IF cart contains Product A
AND cart contains Product B
THEN block checkout
Quantity rules
Set minimums, maximums and pack multiples across a product or a whole group of products.
IF total quantity of Samples > 5
THEN block checkout
Rule simulator
Build a test cart and see exactly which rules pass, fail or are skipped — and the message a shopper would see — before a rule goes live.
Checkout validation
Rules compile into configuration stored inside Shopify and are evaluated by a Shopify Function, so enforcement does not depend on CartGuard being reachable.
Your message, your words
Every rule carries the message the shopper sees at checkout, with an optional Spanish translation on Growth and Pro.
How it works
Four steps, no checkout code
1 · Build a rule
Pick the products it watches and what must — or must not — be in the cart alongside them.
2 · Simulate it
Run a test cart through the same engine that runs at checkout and check the result.
3 · Activate
CartGuard compiles your rules and publishes them to Shopify as checkout validation.
4 · Invalid carts stop
A cart that breaks a rule cannot complete checkout, and the shopper sees your message explaining why.
Pricing
Every plan starts with a 15-day free trial
Basic
$5
USD / month
15-day free trial
- Up to 10 active rules
- Checkout validation
- Rule simulator
- 30 days of history
Growth
$10
USD / month
15-day free trial
- Up to 50 active rules
- Everything in Basic
- Priorities and exclusions
- Customer tag and country targeting
- Translated messages
- 90 days of history
Pro
$20
USD / month
15-day free trial
- Up to 250 active rules
- Everything in Growth
- Multiple rule sets
- Audit trail
- 365 days of history
- Priority support
FAQ
Questions merchants ask
Does checkout depend on CartGuard staying online?
No. Rules are compiled into configuration stored inside Shopify and evaluated by a Shopify Function. If CartGuard's backend is unavailable, your published rules keep working.
What happens if my subscription ends?
CartGuard stops blocking carts. Your rules are kept exactly as they are and resume when you choose a plan again. A lapsed subscription never costs you a sale.
Does it work with express checkouts?
Yes. Shopify's cart and checkout validation runs for Shop Pay, PayPal, Google Pay and Apple Pay as well as the standard checkout.
What customer data does CartGuard store?
None. CartGuard stores your rules and configuration history. It does not store carts, orders or any customer personal information.
Get started
CartGuard installs from the Shopify App Store
Installation happens inside Shopify, so your store stays in control of permissions and billing. Find CartGuard in the Shopify App Store, install it on your store, and your 15-day free trial starts when you choose a plan.