Split's localhost mode with JSON files enables developers to experiment with feature flags offline, enhancing productivity during internet interruptions or while traveling. This feature is accessible through Split's server-side SDKs for Java, Go, and Python, allowing users to download and locally store Split environment definitions and user segments in JSON format. By using the reserved word "localhost" in the Split API key, developers can direct the SDK to utilize local files, ensuring seamless feature flag evaluation even offline. The SDK can regularly poll for changes in these files, facilitating real-time updates and experimentation. This functionality caters to the growing digital nomad trend and provides flexibility to developers working in varying environments. Additionally, Split's Feature Data Platform supports feature management and experimentation, offering tools for A/B testing and controlled feature releases without sacrificing speed or reliability.