A few weeks ago, I linked a solution for password-protecting a prototype on Heroku (or really any LAMP server): https://gist.github.com/josefrichter/561dfd823f829f87ec6e.
However for my work, I often have to do this on an Azure (IIS) server. Here's a quick write up for that: http://westonthayer.com/blog/_site/2015/10/23/hosting-framer-on-azure/.
Thanks for posting this... I finally have to use this!
Cool, thanks for the write up.