The WhatsApp API pricing operates on a conversation-based model, where businesses are charged per session within a 24-hour window for all messages exchanged with a contact.

This pricing structure includes different conversation types such as Marketing, Utility, Authentication, and Service conversations, each with varying costs. Marketing conversations, related to business promotions, tend to be the most expensive, while Authentication conversations, providing one-time passcodes, are usually the cheapest.

User-initiated conversations, like customer service inquiries, fall under a separate pricing category. Additionally, WhatsApp charges different prices based on the country, and businesses need to create templates for different conversation types, which must be approved by Meta before sending.

The pricing model aims to incentivize timely responses from businesses and ensure trust in WhatsApp as a communication channel.