Supported or used or being experimented with or what?
Java, C++, Python, Golang, and Swift/ObfC for iOS apps
No JavaScript? Or is that because it's not used internally but in the public internet?
Google's "big" client apps (Inbox / Gmail / Calendar) are a mix of Java converted to JS (GWT) and native JS with the Closure library/compiler. I think, anyway.
Not sure if GWT is still that relevant nowadays. AngularJS was developed by Google many years ago. It was already pure JS.
Inbox by Gmail launched in 2014, long after Angular JS was first released, and uses GWT.
Close. Apps is using mostly using j2cl.
As addition to JavaScript, they have used their own language called Dart for some their services like AdWords or AdSense [1].