How to access a single-user server API from the hub API?

In the Jupyterhub REST API documentation, there is a somewhat cryptic paragraph that says:

The same API token can also authorize access to the Jupyter Notebook REST API provided by notebook servers managed by JupyterHub if one of the following is true:

  1. The token is for the same user as the owner of the notebook
  2. The token is tied to an admin user or service and c.JupyterHub.admin_access is set to True

Well my c.JupyterHub.admin_access is set to True, and I have an admin token. So what is next? I can startup a server for a user, but how do I access the server’s API to, for instance, put some content? I’ve tried to guess the correct path, but nothing seems to work. Why isn’t the documentation more explicit?

Many thanks in advance for your help.

After a user’s server is started all requests are proxied straight through to it, so you can use the notebook server API:

You can see the API in action at e.g.