A service like this wouldn't cost that much to run even at a scale that serves tens of millions of requests a day. It's pretty much ideal for horizontal scaling. It's certainly in the region where a benevolent Bay Area dev could afford to run it as a hobby.

A single instance of MongoDB and node can handle quite a lot. Anyone who needs this service as a critical component of their product can cheaply host their own version of this or risk downtime/slowness that'd affect their bottom line. (Although for commercial uses you'd use something more featured and secure anyway.)

Looks like the repository is the server implementation. If you can really use this for critical code, it's probably nicest to set up your own server :)