India has the largest number of WhatsApp users. Its enormous population, widespread smartphone adoption, and strong use of mobile messaging helped make India WhatsApp’s biggest national market by total users.
WhatsApp passed 50 million monthly active users in India in May 2014 and reached 70 million by October that year. By February 2017, the Indian user base had grown to 200 million monthly active users. These figures helped establish India as one of the central markets in WhatsApp’s global expansion.
Brazil and Indonesia are also major WhatsApp markets, which can make them tempting alternatives in a quiz. The United States has historically had a lower share of messaging-app usage than India, although WhatsApp has continued growing there. “Largest number of users” means the largest absolute user base, not the highest percentage of a country’s population using the app.