The WhatsApp Business API and RCS are two ways in which a company's own software can send messages to customers and hold whole conversations with them, including a product catalogue and a payment. The WhatsApp Business API connects the company's software to WhatsApp. RCS, short for Rich Communication Services, does a similar job inside the ordinary messaging app on Android phones, and on iPhones on the Jio network. Businesses use both to go beyond plain SMS.
WhatsApp has a free app for small businesses, used on one phone and up to four linked devices. The API is for companies that need many staff on one number, a chatbot, or thousands of messages a day. An API is a fixed format in which one program asks another to do something. Most companies do not connect to WhatsApp directly. They connect through a messaging company, which provides the connection, a dashboard and a tool for building chatbots.
Take, for example, a sweet shop chain in Surat in the week before Diwali. A customer sends "Hi" to the shop's WhatsApp number. The chatbot replies with three buttons: "Order sweets", "Track my order" and "Talk to us". She taps "Order sweets". The bot shows a catalogue, a scrollable list of products with photos and prices, inside the chat. She picks two boxes of kaju katli at ₹650 each. The bot shows a total of ₹1,300 and a Pay button. She pays with UPI without leaving WhatsApp. The shop's payment gateway receives the payment and tells the bot. The bot then confirms the order and the delivery time.
Two WhatsApp rules shape this business. First, a business may message a customer first only with a template, a message whose wording WhatsApp has approved in advance. A shipping update or a festival offer is sent this way. Second, once the customer writes to the business, the business may reply in any wording for the next 24 hours. Meta, the company that owns WhatsApp, charges the business for each template message that is delivered. The rates differ for marketing messages, utility messages such as a shipping update, and login-code messages. Since October 2026, Meta also charges for replies inside the 24-hour window, after the first 1,000 such replies each month on each business number.
RCS needs no extra app. The business's messages appear in the phone's default messaging app, with the business's verified name and logo, photos and buttons. If a phone or an operator does not support RCS, the message is usually sent as an ordinary SMS instead, through an A2P SMS aggregator.
More and more of these chats are now held by AI customer service agents instead of fixed button menus. Companies build them on a conversational AI platform. Marketing teams send their offers to customers who have agreed to receive them, through a WhatsApp marketing platform.