The magic of the client selector is "Profile Linking." Most modern selectors allow you to bind specific server IPs to specific clients.
You can either link directly to other sites or host the Eaglercraft .html files locally within your repository for a seamless experience. eaglercraft-client-selector
Each client receives a unique storagePrefix . ECS intercepts localStorage and IndexedDB calls inside the iframe (via Object.defineProperty on the iframe’s window proxy) and remaps keys to prefix + originalKey . This prevents worlds/settings from leaking between clients. The magic of the client selector is "Profile Linking
GitHub Pages is the most popular choice because it is free and provides a clean URL. eaglercraft-client-selector