Multi-document HTML/CSS/JS code collaboration tools? (vs jsFiddle)

Multi-document HTML/CSS/JS code collaboration tools? (vs jsFiddle)

It's been obvious for some time that jsFiddle is not the best way to set-up jQuery Mobile demos. While it is generally an OK way to show a jQuery problem, it falls short for jQuery Mobile, because it is limited (except for "external resources") to a single CSS, HTML, and JS file. While you can include external resources, of course they can't be edited.

As well, it's not easy or even possible in many cases to show the use of, say, a REST API. So, another "would be nice" would be the ability to proxy URLs to some other site, making it possible to demo access to an API without cross-domain issues.

I'd like to be able to recommend an alternative instead of jsFiddle, and I'd like to solicit input.

I'm aware of one site that seems promising, Plunker. (Note the spelling in the URL, though!)

I haven't spent much time with it, but it does have one important feature needed to effectively demo/collaborate on jQuery Mobile - you can create and edit multiple files. And, so, it's possible to create multi-page demos without being forced to use a multi-page document.

Please comment here if you have used Plunker, or if you have alternative suggestions!