Recombee
Recombee is a real-time recommendation service, which means it returns the recommendations immediately after getting information about the user's action on your website or in your app. This is very important because you can deliver in-the-moment recommendations. For example, when your user adds a product to the shopping cart, you can recommend "frequently-bought-together products" on the next page. Recombee provides you with recommendations based on behavioral patterns (so-called collaborative filtering) and on attributes of products and customers (so-called content-based recommendation). It appropriately combines the methods and adapts and tunes the recommendations based on the collected feedback when launched (there you go, artificial intelligence).