We're actually moving to guest login and we will be removing the necessity to login but thanks for your feedback.

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 :).