Cart Control lets shoppers edit their cart directly inside checkout - changing a variant, adjusting quantity, or removing an item - instead of going back to the cart page. Removing that friction reduces abandonment, while you stay in control of which edits are allowed (so upsell and subscription items can be protected).
What shoppers can do (when enabled)
Each capability is toggled on or off independently:
Change Variant - choose a different in-stock variant (size, color, etc.); price and availability update instantly. Hidden automatically for single-variant products.
Edit Quantity - a +/– selector on each line item; subtotal, shipping, discounts, and tax recalculate in real time.
Remove Items - remove a line item from checkout.
Show Subscription Selector - update the subscription plan; shown only for products that support subscriptions.
Setting it up in PDQ
Go to Extensions → Add Extension and choose Cart Control. The extension has four tabs: Settings, Configurations, Display Conditions, and Installation.
Settings
Internal Name (required) - organizes your extensions; not shown to shoppers.
Internal Description (optional) - an internal note.
Configurations
Button Label - the text on the edit button (e.g. "Edit").
Button Appearance - the button style: Base, Accent, Decorative, Interactive, Subdued, Info, Success, Warning, Critical, or Monochrome.
Allow Customers To - turn each capability on or off: Change Variant, Edit Quantity, Remove Items, and Show Subscription Selector.
Exceptions
Under Exceptions you can override the configuration for items added by PDQ upsells, so they can have different edit permissions than the rest of the cart. Each group has its own Change Variant / Edit Quantity / Remove Items toggles:
Gift Items
Checkout Upsell
Digital Upsell
This is how you keep upsell or gift items locked (for example, not removable) while still letting shoppers edit their core items.
Display Conditions
Use Display Conditions to control when and for whom the extension appears ("This Extension Will Only Appear If…"). Each rule is Field + Operator + Value, and rules combine with AND/OR. Fields include cart value, coupons, customer order count, customer tags, destinations, item count, product tag, SKU, and more.
Installation
On the Installation tab, copy the Token for Shopify (format cart_control_…) to paste into Shopify.
Installing in Shopify
Cart Control attaches to the cart line items, so it goes under Order summary → Cart:
In Shopify, go to Settings → Checkout and click Customize on your live checkout.
Under Order summary → Cart → Items in cart, click Add block and add PDQ Cart Control.
Paste the token into Enter desired cart control token.
Click Save.
What the shopper sees at checkout
An Edit control appears on the cart line item. Expanding it reveals the actions you enabled - a quantity stepper, a remove action, and variant/subscription selectors where applicable. Totals recalculate in real time.
Good to know
Single-variant products: the variant selector is hidden automatically.
Removing the last item: once the cart hits zero, Shopify redirects the shopper to the store's /cart page (standard Shopify behaviour). If the store has no working /cart page, this can land on a 404.
Quantity edits on a discounted item: increasing the quantity may add the extra unit as a separate line item so the discount isn't applied again. This is intentional.