When I first started playing around with putting z-score calculators on the web, I was learning as I went both with writing code as well as "maintaining" it. I learned about version control and played around with SVN.
Eagerly, I put all of this early code on Google's code hosting site, code.google.com.
In January of 2016, Google will be shutting that service down.
All of my current code is now hosted at Bitbucket (one project is on Github) so I won't miss the code hosting. But there is one little calculator hosted over there that I do use sometimes, so I just ported that over to this site: The CHOP TTTS Fetal CV Profile.