> The following {helpers} = require 'chaplin' is easy enough.

I'm not super opposed to this, but it's sorta creating a secret second singleton -- even if helpers isn't implemented as a singleton, it's piggybacking off mediator and so effectively behaves like a singleton.

> to which one utils.serialize should belong in this case?

A good question. The current implementation of `serialize` is very simple and portable and could easily stay in `utils`. The one reason you could move it to helpers is if you want it to be treated as a *Chaplin-specific* serialization scheme - i.e. if you think in the future you'll want to add some crazy extensions to that function to help Chaplin serialize things better.