However, it's clearly insecure so I can't recommend it to anyone.
You say a login is required to run code but I can simply enable the Submit button and everything works? That's just extremely poor design.
The same is true for all of your stuff behind your "paywall." Simply editing the HTML in an editor renders your site usable.
You need to have validation on the server and the client. Simply providing client-side validation is not enough, especially for something that should be considered a teacher or tutorial.
The login is required because otherwise we can't save and pre-load the code for you the next time you visit the same activity.
Edit: what I mean to say is the app itself is secure and so is our sandbox that runs the code and this is more of a UI issue that we'll fix immediately by removing the login prompt.
Edit: The paywall is going away as well :).
As I said, it's a cool idea, but if you want developers to recommend this to people starting out, you need to make those developers confident that they're giving people something well-written and secure.
Edit: Well, cheers to your edits! As someone who is often helping people with learning PHP, I will definitely keep an eye on this project as something to recommend :)
http://blog.unclassroom.com/2012/03/getting-on-hn-front-page...
