Yeah I actually started building a custom solution using codemirror and node.js, but with my limited web development skills it seemed like it was going to take a long time to get the quality I needed. I might go back to that if I can't find anything else that makes the development easier. What we really need is a input/output coding quiz system like leetcode, and then on top of that having a collaborative sandbox coding environment for tutors and students to work together on would be great. I think the biggest challenge might be supporting multiple coding languages.