You have a promo code, but the product page has nowhere to put it. In most cases, you enter it on the retailer's own cart or checkout page, before you confirm the order. A ShopTools search box is not a coupon field, and payment details are not one either. The exact location depends on the retailer's checkout.
Add the items you actually want, then open the cart. Look for labels such as “Promo code”, “Discount code”, “Coupon” or “Have a code?”. If nothing appears, continue to checkout and inspect the order summary. Do not press a payment or place-order button just to hunt for a field.
Why the field moves between cart and checkout
WooCommerce's merchant documentation describes customers opening “Add Coupon” on a cart or checkout page, entering the code and pressing a separate “Apply” button. Shopify says shoppers enter discount codes at checkout. Those are examples of two platforms, not proof that any particular retailer uses either layout.
The field may sit in the order summary rather than next to the items. On a small screen, that summary may be collapsed: Shopify documents a mobile checkout design in which tapping the summary reveals the details and discount-code field. Not seeing the field in the first mobile view is therefore not evidence that no code can be used.
If the field never appears
Check that you have selected the product variant and delivery option, then look for a coupon link around the order summary. Do not paste a code into gift-card, phone, address or payment fields. Their proximity to the total does not make them interchangeable.
Sometimes the checkout flow itself hides the option. Shopify says the field may be absent when no active code is available, for some draft-order links, or when an app changes checkout; with Shop Pay, the field appears after the customer signs in. These are Shopify-specific possibilities, not a diagnosis of every store. If the retailer provides no visible way to enter a code, consult its own instructions or support rather than trying to bypass the process or placing a dummy order.
After applying the code, check the amount due
Entering and applying are different steps. Paste the code accurately, use the store's Apply button if one is shown, wait for a recalculation and compare the amount due for the same items, delivery and currency. An accepted-code message need not mean a lower payment: an offer may affect shipping, a gift or only eligible products. If the store rejects the code, read its message and promotion terms instead of repeating the same attempt.
ShopTools helps you find a code without installing the extension, but you enter it at the retailer. You start a separate extension check on a supported cart; that is not a promise of universal checkout support. Some ShopTools visits use affiliate links, and the service may earn a commission from a confirmed purchase. A visit does not apply a coupon, and the service's commission is not cashback paid to you.
If you cannot find the field or understand the effect before paying, rely on the retailer's final price. You need not enter payment details merely to test a code, and a missing discount does not oblige you to finish the purchase.