Nowadays opensource alternatives for html5 panorama viewing are at least 2: Pannellum and Panovisu !
Panovisu results of a Frenchs initiative : not only it displays your equirectangular or cubic panos, but you can make a complete VR tour with its java editor !
You’ll need a very recent java installation on your computer to launch it, it has been tested on all recent browsers : all webGL activated are ok but Safari ( as far as I know)
Lets link to its website: www.panovisu.fr
I can help to translate if you don’t read or speak french !
There a personal demo of mine :
Enjoy it , let me know any bug or problem, I would back them up to its dev !