This is really cool to see, but also somewhat depressing because it reminds me that I spent about 500 hours of my free time building the same thing, and even had it deployed at codetrain.io for a while, but then lost interest and now my code's wasting away in a private bitbucket repo.
Before I shut mine down it could run 13 or so different languages, spin up collaborative REPLs for Node.js/Python/Ruby, and organize snippets into tutorials/lessions, etc. It was awesome, but now sits in my side project graveyard. It's a shame really.
Glad to see glot.io getting more attention.