Splash is a javascript rendering service with an HTTP API. It's a lightweight browser with an HTTP API, implemented in Python using Twisted and QT.
It's fast, lightweight and state-less which makes it easy to distribute.
Documentation is available here: http://splash.readthedocs.org/
Open source support is provided here in Github. Please create a question issue (ie. issue with "question" label).
Commercial support is also available by Scrapinghub.