Feature Requests

Manual testing of challenges to ensure the example matches the sample data and the wording of the challenge is very clear.

Public and private leaderboards would be fun to compare your performance against other users.

A way to write and run queries on the site. It would be nice if this had different database options and nice SQL formatting. This would facilitate new challenge types like performance optimisations, different DB extensions etc.

Hints should link to videos and resources explaining the concept in more detail.

The ability register and login with Google or Github.

This will help users who wish to go back and refactor or simplify their solutions and allow them to check that their updated SQL remains correct.