Please don't do that. Aside from being a major buzzkill, it probably kills conversion, which I'm sure you find a buzzkill ;) Maybe you could let people try out some challenges and then after N runs, ask them to sign up?
That being said, you have an idea I never thought of. I could simply let any user make X number of attempts and then prompt for registration. It's not as annoying that way and still secure. And yes, it's definitely hurting conversion BUT I couldn't think of any other way to set things up. If anyone else has suggestions on this, I'm all ears!
I understand why you put the registration further into the process. People have already invested time, so they might as well register so that the time isn't wasted. This is markedly different from how the rest are. They either put registration up front (HackerRank) or you're required to validate your own code (cryptopals). Aside from intentionally infecting my computer with malware or something, I couldn't think of a more negative user experience from a code challenge site.
These types of sites are far from unique. They are basically a dime a dozen. But now my experience is, "Don't make the same mistake I did. It gives you an input field to submit a challenge, but it will not validate your answer until you register. Either register up front, or don't bother."
Edit: This post was intended to be constructive, but I can see how it can be interpreted otherwise. See here[0] for more info. Apologies!
That's not constructive criticism. You can't always create something that's unique and not a dime a dozen.
Sometimes the challenges take 30 seconds. Other times, you may spend over 30 minutes working on something more challenging. Who wants to spend time working on a challenge only to be told, "Wait a sec. You need to register before I tell you if you were correct." If I am presented with an input field, I would expect that I am allowed to submit that input. And that's where the dime a dozen comment comes from. If I try to accomplish the task your site has given me but there's an unexpected roadblock imposed by the site itself, why would I stay on that site when I can go elsewhere?
If registration is required, it should say so up front. Allow users to browse challenges. Even allow users to view the full challenge text. However, disable the input field if they must register first. It otherwise implies that I can solve the challenge without an account. You don't want to mislead your potential users.
I supposed I should have said something like, "There are many code challenge sites available. It is imperative to give users a positive experience, because users can easily go elsewhere for something similar." I did not mean to be insulting.
You just nailed it.
Without knowing how you run the code server-side, are there any languages/challenges that are presumably safe? Maybe you could offer the Javascript challenges without the requiring the user to register.
I agree with you.