Duolingo is the world's largest language-learning app. They have over 300 million learners worldwide, teach more than 30 different languages, and the content is entirely free. Duolingo’s mission is to make education free and accessible to everyone. The app is currently available in the Apple App Store, Google Play Store, and other Android App Stores. Duolingo’s headquarters are in Pittsburgh, but they have additional offices in Beijing, New York, and Seattle.

Even though Duolingo is the world’s leading education app, the user base still has a lot more room to grow in China and other Asian markets. Usage and user behavior differ across countries. Duolingo thinks it is really important to provide fast, high-quality, and A+ experiences to all of their users worldwide. In China, they have started working closely with Alibaba Cloud to address these issues.

Duolingo learners complete millions of lessons every day on the app, and as China’s leading cloud provider, Alibaba Cloud was uniquely positioned to help them scale their product and deliver the best experience to Duolingo learners in China.

The most important services Duolingo uses from Alibaba Cloud are CEN and CDN. Duolingo uses Alibaba Cloud CEN to reduce API latency for users in China and to bridge multiple datacenters together and across vendors. The CEN service allows Duolingo to optimize their performance and reduce latency when making network calls across different regions. Since it's efficient to deploy, their engineers don’t need to deal with low level interface and hardware. The engineers can focus on building innovative applications and infrastructure. It’s also worth noting that Duolingo only uses one operations engineer running the app in China’s infrastructure. CDN is another service Duolingo uses to reduce latency when consuming static content. For example, when users do an audio lesson, the latency to download the file is reduced from seconds to hundreds of milliseconds. The files are distributed all over the country, so no matter where users are they all have the same experience.

Duolingo has a small team in China and are always looking for smart solutions to solve hard problems. They are hoping to continue using Alibaba Cloud to build more efficient technical operations and adopt more cutting-edge technology.