RevSpark displays upsell recommendations on the thank you page after checkout. When a customer buys a product, RevSpark checks their order and shows a relevant recommendation for a complementary product. Customers can accept with one click. On Shopify Plus stores, the item is added directly to their existing order. In standard stores, the customer receives an invoice email via new order. Merchants can create rules based on specific products, collections, or apply a global rule for all customers.