In an always-connected world, it's easy to forget that not all users have reliable internet. Rural communities, traveling workers, and developing regions all need apps that work offline. Building local-first applications isn't just a technical choice - it's about making your software accessible to everyone.

But local-first brings complexity across all platforms. Web apps need to handle service workers and cache invalidation securely. PWAs must manage sensitive data across multiple storage mechanisms. Native apps face synchronisation and key management challenges. Each platform introduces unique security considerations that go far beyond simple data encryption.

Through examples and live demonstrations across web, PWA, and native platforms, we'll explore the security landscape of offline-capable apps. You'll see how different platforms handle local storage, where the security boundaries blur, and how to build robust solutions that work everywhere. From secure sync protocols to proper key management, from cache poisoning defences to secure state management, you'll learn patterns that scale across your entire application ecosystem.