[mttjj]

I have an ad-blocker (and a network ad-blocker via the corporate network I'm connected to right now) but when I click on any one of the languages I can see a box labeled "ads via Carbon" to the right of the stdin box. So my guess would be that it's ad-supported for now.

[mosselman]

You'd think that all people interested in something like this have an ad-blocker. I wonder what the revenue is like.