Shared Worker is most similar to Service Worker b/c it is shared between tabs from the same origin. But Shared Worker lifetime is controlled by the app – so you can keep it around as long as it’s useful, and it can be stateful. Service Worker lifetime is controlled by the browser, and is often killed when idle. Service Worker can be started/stopped many times a second (whenever no event handlers are running).

Unfortunately Shared Worker is not yet implemented on Chrome Android, but it is implemented on all other major browsers.

This issue tracks Shared Worker on Chrome Android – hopefully coming soon! And there’s also some discussion on the tradeoffs between Service Worker and Shared Worker.