FlatUpsell adds one-click upsells at two moments: on the cart page before checkout, and just after payment, before the thank-you page, with no card details to re-enter. Set simple rules ("if the cart has X, suggest Y at a discount") by product or collection, no code. A/B test several products after checkout to see which one converts more. See views, acceptance rate and extra revenue on one dashboard, split by placement. The cart-page popup picks up your theme's colors and corner style.

• Post-purchase one-click upsell — no re-entering payment details
• Cart-page upsell when customers click checkout, styled to match your theme
• Simple trigger rules by product or collection — no code required
• Dashboard: views, conversion rate, extra revenue, by placement
• A/B test post-purchase products to see which one converts more