It says it needs Java 6 or 7 + Chrome. So the interface is probably in HTML5 (the Chrome requirement), but the hardware emulators are in Java. You get a tab in

It says it needs Java 6 or 7 + Chrome. So the interface is probably in HTML5 (the Chrome requirement), but the hardware emulators are in Java. You get a tab in Chrome directed at localhost:58888/_emulator/_ide/index.html Coincidentally no new tabs would load in Chrome after I ran that. However, existing tabs were able to load.