Explore the challenges and solutions of scaling offline-first web applications in this JSConf EU 2019 talk. Dive into the complexities of modeling distributed data and developing scalable code for 30,000 clinics in Africa's most populous country. Learn about the evolution of offline-capable web apps, the use of tools like service workers, PouchDB, and CouchDB, and how they address initial implementation questions. Discover strategies for handling data replication, network storage, JSON modeling, and user experience in large-scale offline-first systems. Gain insights into potential pitfalls and planning considerations for growing offline-first applications, with a focus on real-world applications in medical supply systems.