WhatsApp Business is a free app designed specifically for small businesses to improve communication with customers. However, there is also an advanced version called WhatsApp Business Premium, as well as the "WhatsApp Business API," which is designed for medium to large businesses and offers additional features and more intensive integration with existing systems. The cost of the WhatsApp Business API can vary and depends on several factors, including the number of messages you want to send. 1,000 conversations are always free.