Pair Codepen with RdbHost, and you can do full stack development! You can load the RdbHost module into your CodePen 'pen', and do database queries from your pen.
I put together an RdbHost Starter pen, and a quick poll type app there, and found no obstacles or special considerations involved in using RdbHost within CodePen.
A startup sequence is documented in the CodePen Blogpost link below, and a starter template is available through the second link.
With or without RdbHost, you should give CodePen a try; they provide a very elegant medium for quick web dev projects.