Great implementation for a bad practice, idea. This tool IMHO encourages the worst interviewing practices.
I'd prefer to hire like this:
1. Collect resumes/recommendations
2. Ask candidates to implement a simple project (~8 hours)
3. Ask remaining candidates with reasonable/better solutions to come on-site.
4. See how behave during code review of their project
5. Give them a small simple problem to solve
6. Ask them to tell you their solutions time and space complexity
7. Ask them to write a unit test for their solution
8. Ask them to code review your solution to the same simple problem and contrast it to theirs
9. Ask them 1 or 2 simple theory questions that demonstrate their understanding depth. Maybe "How does virtual memory work and why was it invented".
10. Buy them lunch/supper.