Jupyter Server Proxy lets you run arbitrary external processes (such as RStudio, Shiny Server, syncthing, PostgreSQL, etc) alongside your notebook, and provide authenticated web access to them.

Note: This project used to be called nbserverproxy. if you have an older version of nbserverproxy installed, remember to uninstall it before install jupyter-server-proxy - otherwise they may conflict

The primary use cases are:

1. Use with JupyterHub / Binder to allow launching users into web interfaces that have nothing to do with Jupyter - such as RStudio, Shiny, or OpenRefine.
2. Allow access from frontend javascript (in classic notebook or JupyterLab extensions) to access web APIs of other processes running locally in a safe manner. This is used by the JupyterLab extension for dask.

The documentation contains information on installation & usage.