Cart Notices is among the best WooCommerce upsell plugins. It shows dynamic notes to customers just as they are about to leave your site or proceed to checkout, alerting them about a closing sale or encouraging them to buy another related product to avail of free shipping. It works wonders as it creates a sense of urgency in your customers and entices them with amazing offers.
There are multiple shortcodes available that let you place the messages anywhere on site. It also helps in increasing sales and revenue by recommending similar or related products to increase order value.