WeChat is not just a messaging app. With nearly a billion active users, it is used to make voice calls, play games, read news, hail cars and more. With WeChat Pay, people use the app to send money and pay bills by scanning a QR code, and friends and families use WeChat to send lucky money during festivals. For many, WeChat is already indispensable. How did the company grow? What were the key decisions and strategies? In the fierce competition between WeChat pay and Alibaba’s Alipay, who will win? There are many questions about WeChat, but the app’s success is certain—for now.