Duolingo is the free, science-based, language education platform that has organically become the most popular way to learn languages online. With over 200 million users and seven billion language exercises completed each month, the company's mission is to make education free, fun, and accessible to all. "Amazon ElastiCache has played an absolutely critical part in our infrastructure from the beginning," said Max Blaze, Staff Operations Engineer at Duolingo. "As we have grown, we have pushed the limits of what is possible with single-shard clusters. ElastiCache for Redis online resharding will allow us to easily scale our Redis clusters horizontally as we grow, greatly simplifying the management of our many Redis clusters, empowering us to scale quickly while also reducing cost across our caching layers, and continue to grow with minimal changes to our current services.